UNDERWRITING AGREEMENT

EXHIBIT 1.1

UNDERWRITING AGREEMENT

CHITTENDEN CORPORATION

(a Vermont corporation)

$125,000,000 Principal Amount of Subordinated Debt Securities due February 14, 2017

Dated: February 7, 2007

Table of Contents

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$125,000,000

CHITTENDEN CORPORATION

(a Vermont corporation)

Subordinated Debt Securities due February 14, 2017

UNDERWRITING AGREEMENT

Ladies and Gentlemen:

Chittenden Corporation, a Vermont corporation (the “Company”), proposes to issue and sell $125,000,000 aggregate principal amount of its Subordinated Debt Securities due February 14, 2017 (the “Notes”) to the several Underwriters named in Schedule A hereto (collectively the “Underwriters,”), for whom Lehman Brothers Inc. is acting as Representative (in such capacity, the “Representative”). The Notes will be issued pursuant to an Indenture dated as of February 14, 2007 (the “Indenture”) between the Company and The Bank of New York Trust Company, N.A., a national banking association, as Trustee (the “Trustee”). This agreement (this “Agreement”) is to confirm the agreement concerning the purchase of the Notes from the Company by the Underwriters.

The Company has filed with the Securities and Exchange Commission (the “Commission”) a shelf registration statement on Form S-3 (No. 333-87586), as amended by Pre-effective Amendment No. 1 thereto, covering the registration of the Notes under the Securities Act of 1933, as amended (the “1933 Act”), which permits the delayed or continuous offering of securities pursuant to Rule 415 of the rules and regulations of the Commission under the 1933 Act (the “1933 Act Regulations”). Promptly after execution and delivery of this Agreement, the Company will prepare and file a prospectus (including a prospectus supplement relating to the Notes) in accordance with the provisions of Rule 430B (“Rule 430B”) of the 1933 Act Regulations and paragraph (b) of Rule 424 (“Rule 424(b)”) of the 1933 Act Regulations. Any information included in such prospectus that was omitted from such registration statement at the

time it became effective but that is deemed to be part of such registration statement at the time it became effective pursuant to Rule 430B is referred to as “Rule 430B Information.” The term “preliminary prospectus” means a preliminary prospectus supplement specifically relating to the Notes together with a base prospectus. Such registration statement, at any given time, including the exhibits thereto, schedules thereto, if any, and the documents incorporated by reference therein pursuant to Item 12 of Form S-3 under the 1933 Act at such time, and information (including the Rule 430B Information) otherwise deemed to be part thereof or included thereon by 1933 Act Regulations at such time, is herein called the “Registration Statement.” Any registration statement filed pursuant to Rule 462(b) of the 1933 Act Regulations is herein referred to as the “Rule 462(b) Registration Statement,” and after such filing the term “Registration Statement” shall include the Rule 462(b) Registration Statement. The final prospectus, including the documents incorporated by reference therein pursuant to Item 12 of Form S-3 under the 1933 Act, in the form first furnished to the Underwriters for use in connection with the offering of the Notes is herein called the “Prospectus.” For purposes of this Agreement, all references to the Registration Statement, any preliminary prospectus, the Prospectus or any amendment or supplement to any of the foregoing shall be deemed to include the copy filed with the Commission pursuant to its Electronic Data Gathering, Analysis and Retrieval system (“EDGAR”).

All references in this Agreement to financial statements and schedules and other information which is “contained,” “included” or “stated” in the Registration Statement, any preliminary prospectus or the Prospectus (or other references of like import) shall be deemed to mean and include all such financial statements and schedules and other information which is incorporated by reference in the Registration Statement, any preliminary prospectus or the Prospectus, as the case may be; and all references in this Agreement to amendments or supplements to the Registration Statement, any preliminary prospectus or the Prospectus shall be deemed to mean and include the filing of any document under the Securities Exchange Act of 1934, as amended (the “1934 Act”) which is incorporated by reference in the Registration Statement, any preliminary prospectus or the Prospectus, as the case may be.

SECTION 1. Representations and Warranties.

(a) Representations and Warranties by the Company . The Company represents and warrants to each Underwriter as of the date hereof, the Applicable Time (referred to in Section 1(a)(i) hereof) and as of the Closing Time (referred to in Section 2(b) hereof) (in each case, a “Representation Date”), and agrees with each Underwriter, as follows:

(i) Compliance with Registration Requirements. The Company meets the requirements for use of Form S-3 under the 1933 Act and has not been, and continues not to be, an “ineligible issuer” (as such term is defined in Rule 405 of 1933 Act Regulations) at all times relevant under the 1933 Act in connection with the offering of the Notes. Each of the Registration Statement and any Rule 462(b) Registration Statement has become effective under the 1933 Act and no stop order suspending the effectiveness of the Registration Statement or any Rule 462(b) Registration Statement has been issued under the 1933 Act and no proceedings for that purpose have been instituted or are pending or, to the knowledge of the Company, are contemplated by the Commission, and any request on the part of the Commission for additional information has been complied with.

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At the respective times the Registration Statement, any Rule 462(b) Registration Statement and any post-effective amendments thereto became effective, and at each Representation Date, the Registration Statement, the Rule 462(b) Registration Statement and any amendments and supplements thereto complied and will comply in all material respects with the requirements of the 1933 Act and the 1933 Act Regulations and the Trust Indenture Act of 1939 (the “1939 Act”) and the rules and regulations of the Commission under the 1939 Act (the “1939 Act Regulations”) and did not and will not contain an untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein not misleading.

Neither the Prospectus nor any amendments or supplements thereto, as of the applicable date of the Prospectus or any such amendment or supplement and at the Closing Time included or will include an untrue statement of a material fact or omitted or will omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading.

Each preliminary prospectus and the preliminary prospectus filed as part of the Registration Statement as originally filed or as part of any amendment thereto, or filed pursuant to Rule 424 under the 1933 Act, complied when so filed in all material respects with the 1933 Act Regulations, and any preliminary prospectus and the Prospectus delivered to the Underwriters for use in connection with this offering was identical to the electronically transmitted copies thereof filed with the Commission pursuant to EDGAR, except to the extent permitted by Regulation S-T.

As used in this subsection and elsewhere in this Agreement,

“Applicable Time” means 4:15 p.m. (New York City time) on the date of this Agreement;

“Disclosure Package” means, as of the Applicable Time, the most recent preliminary prospectus, together with each Issuer Free Writing Prospectus filed or used by the Company on or before the Applicable Time and identified on Schedule B hereto, other than a road show that is an Issuer Free Writing Prospectus under Rule 433 of the 1933 Act Regulations;

“Final Term Sheet” means the term sheet prepared pursuant to Section 3(b) of the Agreement and substantially in the form attached in Schedule C hereto;

“Issuer Free Writing Prospectus” means each “free writing prospectus” (as defined in Rule 405 of the 1933 Act Regulations) prepared by or on behalf of the Company or used or referred to by the Company in connection with the offering of the Notes, including the Final Term Sheet;

“Most recent preliminary prospectus” means the latest preliminary prospectus included in the Registration Statement or filed pursuant to Rule 424(b) of the 1933 Act Regulations prior to the date hereof.

The Disclosure Package did not, as of the Applicable Time, contain any untrue statement of a material fact or omit to state any material fact required to be stated therein or necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading.

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The representations and warranties in this subsection shall not apply to statements in or omissions from the Registration Statement, Prospectus or the Disclosure Package made in reliance upon and in conformity with information furnished to the Company in writing by or on behalf of any Underwriter through the Representative expressly for use therein or to that part of the Registration Statement that constitutes the Statements of Eligibility and Qualification on Forms T-1 (the “Forms T-1”) under the 1939 Act of the Trustee.

(ii) Incorporated Documents. The documents incorporated or deemed to be incorporated by reference in any preliminary prospectus or the Prospectus, at the time they were or hereafter are filed with the Commission, complied and will comply in all material respects with the requirements of the 1934 Act and the rules and regulations of the Commission thereunder (the “1934 Act Regulations”) and did not and will not contain an untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading.

(iii) Independent Accountants. PriceWaterhouseCoopers LLP, the accountants who certified the financial statements and supporting schedules included in the Registration Statement are independent public accountants as required by the 1933 Act and the 1933 Act Regulations and the rules and regulations of the Public Company Accounting Oversight Board.

(iv) Financial Statements. The consolidated financial statements incorporated by reference in the Registration Statement, the Disclosure Package and the Prospectus, together with the related schedules and notes, present fairly, in all material respects, the consolidated financial position of the Company and its consolidated subsidiaries at the dates indicated and the statement of operations, stockholders’ equity and cash flows of the Company and its consolidated subsidiaries for the periods specified; except as otherwise noted therein, said financial statements have been prepared in conformity with generally accepted accounting principles (“GAAP”) applied on a consistent basis throughout the periods involved. The supporting schedules, if any, included in the Registration Statement, the Disclosure Package and the Prospectus present fairly in all material respects and in accordance with GAAP the information required to be stated therein. The selected financial data set forth under the caption “Selected Financial Data” in the Prospectus present fairly, in all material respects, the information shown therein and have been compiled on a basis consistent with that of the audited financial statements incorporated by reference in the Registration Statement (except as otherwise noted therein).

(v) No Material Adverse Change in Business. Since the respective dates as of which information is given in the Registration Statement, the Disclosure Package and the Prospectus, except as otherwise stated therein, (A) there has been no material adverse change in the condition, financial or otherwise, or in the earnings or business affairs of the Company and its subsidiaries considered as one enterprise, whether or not arising in the ordinary course of business (a “Material Adverse Effect”), (B) there have been no transactions entered into by the Company or any of its subsidiaries, other than those in the ordinary course of business, which are

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material with respect to the Company and its subsidiaries considered as one enterprise and (C) there has been no dividend or distribution of any kind declared, paid or made by the Company on any class of its capital stock, except for dividends paid by the Company in the ordinary course of business consistent with past practice.

(vi) Good Standing of the Company. The Company has been duly organized and is validly existing as a corporation in good standing under the laws of the State of Vermont and has corporate power and authority to own, lease and operate its properties and to conduct its business as described in the Disclosure Package and the Prospectus and to enter into and perform its obligations under this Agreement; the Company is duly qualified as a foreign corporation to transact business and is in good standing in each other jurisdiction in which such qualification is required, whether by reason of the ownership or leasing of property or the conduct of business, except where the failure so to qualify or to be in good standing would not result in a Material Adverse Effect; and the Company is duly registered as a bank holding company under the Bank Holding Company Act of 1956, as amended.

(vii) Good Standing of Subsidiaries. Each “significant subsidiary” of the Company (as such term is defined in Rule 405 of the 1933 Act Regulations) (each a “Subsidiary” and collectively, the “Subsidiaries”) has been duly organized and is validly existing as a trust company or depository institution in good standing under the laws of the jurisdiction in which it is chartered or organized, has full corporate, trust company or depository institution, as applicable, power and authority to own, lease and operate its properties and to conduct its business as described in the Disclosure Package and the Prospectus and is duly qualified to transact business and is in good standing in each jurisdiction in which such qualification is required, whether by reason of the ownership or leasing of property or the conduct of business, except for such jurisdictions where the failure to be so qualified or to be in good standing would not result in a Material Adverse Effect; all of the issued and outstanding capital stock of each such Subsidiary has been duly authorized and validly issued, is fully paid and non-assessable and is owned by the Company, directly or through subsidiaries, free and clear of any security interest, mortgage, pledge, lien, encumbrance, claim or equity; and none of the outstanding shares of capital stock of any such Subsidiary was issued in violation of the preemptive or similar rights of any security holder of that subsidiary. The Company has no subsidiaries which would constitute a “significant subsidiary” as such term is defined in Rule 405 other than Chittenden Trust Company, The Bank of Western Massachusetts and Ocean National Bank.

(viii) FDI Act. Each Subsidiary is an insured depository institution under the provisions of the Federal Deposit Insurance Act, as amended (the “FDI Act”)

(ix) Authorization of Indenture. The Indenture has been duly authorized by the Company and duly qualified under the 1939 Act, and when duly executed and delivered by the Company and assuming the due authorization, execution and delivery of the Indenture by the Trustee, will constitute a valid and binding agreement of the Company, enforceable against the Company in accordance with its terms, except as enforcement thereof may be limited by bankruptcy, insolvency (including, without limitation, all laws relating to fraudulent transfers), reorganization, moratorium or similar laws affecting enforcement of creditors’ rights generally and except as enforcement thereof is subject to general principles of equity (regardless of whether enforcement is considered in a proceeding in equity or at law).

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(x) Authorization of Notes. The Notes have been duly authorized by the Company, and when executed, authenticated, issued and delivered in the manner provided for in the Indenture and sold and paid for as provided in this Agreement, the Notes will constitute valid and binding obligations of the Company entitled to the benefits of the Indenture and enforceable against the Company in accordance with their terms, except as enforcement thereof may be limited by bankruptcy, insolvency (including, without limitation, all laws relating to fraudulent transfers), reorganization, moratorium or similar laws affecting enforcement of creditors’ rights generally and except as enforcement thereof is subject to general principles of equity (regardless of whether enforcement is considered in a proceeding in equity or at law).

(xi) Authorization of Agreement. This Agreement has been duly authorized, executed and delivered by the Company.

(xii) Capitalization. The authorized, issued and outstanding capital stock of the Company is as set forth in the Disclosure Package and the Prospectus in the column entitled “Actual” under the caption “Capitalization” (except for subsequent issuances, if any, pursuant to this Agreement, pursuant to reservations, agreements or employee benefit plans referred to in the Disclosure Package and the Prospectus, pursuant to the Company’s dividend reinvestment plan or pursuant to the exercise of convertible securities or options referred to in the Disclosure Package and the Prospectus). The shares of issued and outstanding capital stock of the Company have been duly authorized and validly issued and are fully paid and non-assessable; none of the outstanding shares of capital stock of the Company was issued in violation of the preemptive or other similar rights of any securityholder of the Company.

(xiii) Absence of Defaults and Conflicts. Neither the Company or its subsidiaries is in violation of its charter or by-laws or other organizational documents or in default in the performance or observance of any obligation, agreement, covenant or condition contained in any contract, indenture, mortgage, deed of trust, loan or credit agreement, note, lease or other agreement or instrument to which the Company or any subsidiary of the Company is a party or by which any of them may be bound, or to which any of the property or assets of the Company or any subsidiary of the Company is subject, except for such defaults that would not result in a Material Adverse Effect; and the execution and delivery by the Company, and the performance by the Company of its obligations under this Agreement, the Indenture and the Notes, the issuance and delivery of the Notes and the fulfillment of the terms contemplated herein and therein do not and will not, whether with or without the giving of notice or passage of time or both, conflict with or constitute a breach of, or default under or Repayment Event (as defined below) under, or result in the creation or imposition of any lien, charge or encumbrance upon any property or assets of the Company or any of its subsidiaries pursuant to, any contract, indenture, mortgage, deed of trust, loan agreement, guarantee, lease, financing agreement or other similar agreement or instrument to which the Company or any of its subsidiaries is a party or by which the Company or any of its subsidiaries is bound or to which any of the property or assets of the Company or any of its subsidiaries is subject, except, in each case, as would not result in a Material Adverse Effect or would not result in a material adverse change in the power or ability of the Company to perform its obligations under this Agreement, the Indenture or the Notes or to consummate the transactions to be performed by it as set forth in or contemplated in the Disclosure Package and the Prospectus, nor will such actions result in any violation of the provisions of the charter or by-laws of the Company or any subsidiary, nor will such actions

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result in any violation (in each case material to the Company and its subsidiaries considered as a whole) of any statute or any order, rule or regulation of any court or regulatory authority or other governmental body having jurisdiction over the Company or any of its subsidiaries or any of their properties; and no consent, approval, license, registration, decree, authorization or order of, or filing or qualification with, any court or governmental body or agency is required for, and the absence of which would materially affect, the performance by the Company of its obligations under this Agreement, in connection with the offering, issuance or sale of the Notes hereunder or the consummation of the transactions contemplated by this Agreement or for the due execution, delivery or performance of the Indenture by the Company, except such as have already been obtained or as may be required under the 1933 Act, the 1934 Act or the state securities laws of the various states in connection with the sale of the Notes and except for the qualification of the Indenture under the 1939 Act. As used herein, a “Repayment Event” means any event or condition which gives the holder of any note, debenture or other evidence of indebtedness (or any person acting on such holder’s behalf) the right to require the repurchase, redemption or repayment of all or a portion of such indebtedness by the Company or any subsidiary in advance of the contractual maturity of such indebtedness.

(xiv) Absence of Labor Dispute. No labor dispute with the employees of the Company or any subsidiary of the Company exists or, to the knowledge of the Company, is imminent that may reasonably be expected to result in a Material Adverse Effect.

(xv) Absence of Proceedings. There is no action, suit, proceeding, inquiry or investigation before or brought by any court or regulatory or governmental agency or body, domestic or foreign, now pending, or, to the knowledge of the Company, threatened, against or affecting the Company or any subsidiary, which is required to be disclosed in the Registration Statement, Disclosure Package or the Prospectus (other than as disclosed therein), or which might reasonably be expected to result in a Material Adverse Effect, or which might reasonably be expected to materially and adversely affect the consummation of the transactions contemplated in this Agreement or the performance by the Company of its obligations hereunder; the aggregate of all pending legal or regulatory or governmental proceedings to which the Company or any subsidiary of the Company is a party or of which any of their respective property or assets is the subject which are not described in the Registration Statement, Disclosure Package or the Prospectus including ordinary routine litigation incidental to the business, would not reasonably be expected to result in a Material Adverse Effect.

(xvi) Possession of Insurance. The Company and its subsidiaries carry or are entitled to the benefits of insurance in such amounts and covering such risks as is generally deemed adequate for its business and consistent with insurance coverage maintained by companies of similar size and scope of operations in similar businesses, and all such insurance is in full force and effect.

(xvii) Possession of Intellectual Property. The Company and its subsidiaries own or possess or can acquire on reasonable terms, the patents, patent rights, licenses, inventions, copyrights, know-how (including trade secrets and other unpatented and/or unpatentable proprietary or confidential information, systems or procedures), trademarks, service marks and trade names (collectively, “patent and proprietary rights”) presently employed by them in connection with the business now operated by them as described in the Prospectus,

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except where lack thereof would not result in a Material Adverse Effect, and the Company and its subsidiaries have not received any written notice of any infringement of or conflict with asserted rights of others with respect to any patent or proprietary rights or of any facts or circumstances which would render any patent and proprietary rights invalid or inadequate to protect the interest of the Company and its subsidiaries therein, and which infringement or conflict (if the subject of any unfavorable decision, ruling or finding) or invalidity or inadequacy, singly or in the aggregate, would result in any Material Adverse Effect.

(xviii) Possession of Licenses and Permits. The Company and its subsidiaries possess such permits, licenses, approvals, consents and other authorizations (collectively, “Governmental Licenses”) issued by the appropriate federal, state, local or foreign regulatory agencies or bodies necessary to conduct the business now operated by them, except for such Governmental Licenses the absence of which would not reasonably be expected to cause a Material Adverse Effect; the Company and its subsidiaries are in compliance with the terms and conditions of all such Governmental Licenses, except where the failure so to comply would not reasonably be expected to, singly or in the aggregate, have a Material Adverse Effect; all of the Governmental Licenses are valid and in full force and effect, except when the invalidity of such Governmental Licenses or the failure of such Governmental Licenses to be in full force and effect would not have a Material Adverse Effect; and neither the Company nor any of its subsidiaries has received any notice of proceedings relating to the revocation or modification of any such Governmental Licenses which, singly or in the aggregate, if the subject of an unfavorable decision, ruling or finding, would result in a Material Adverse Effect.

(xix) Manipulation. The Company and its subsidiaries have not taken and will not take, directly or indirectly, any action designed to or which constituted or which might reasonably be expected to cause or result in stabilization or manipulation of the price of the Notes.

(xx) Investment Company Act. The Company is not, and upon the issuance and sale of the Notes as herein contemplated and the application of the net proceeds therefrom as described in the Disclosure Package and the Prospectus will not be, an “investment company” or an entity “controlled” by an “investment company” as such terms are defined in the Investment Company Act of 1940, as amended (the “1940 Act”).

(xxi) Other Contracts. Other than such agreements, contracts and other documents as are described in the Disclosure Package and the Prospectus or otherwise filed as Exhibits to the Registration Statement or to the Company’s annual report on Form 10-K, quarterly reports on Form 10-Q or current reports on Form 8-K incorporated by reference in the Prospectus, there are no agreements, contracts or documents of a character described in Item 601 of Regulation S-K of the Commission to which the Company or any of its Subsidiaries is a party.

(xxii) Title to Property. The Company and its subsidiaries have good and marketable title to all real property owned by the Company and its subsidiaries and good title to all other properties owned by them that are material to the business of the Company and its subsidiaries, considered as one enterprise, in each case, free and clear of all mortgages, pledges, liens, security interests, claims, restrictions or encumbrances of any kind except such as (a) are described in the Disclosure Package and the Prospectus or (b) do not, singly or in the aggregate,

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materially affect the value of such property and do not interfere with the use made and proposed to be made of such property by the Company or any of its subsidiaries; and all of the leases and subleases material to the business of the Company and its subsidiaries, considered as one enterprise, and under which the Company or any of its subsidiaries holds properties described in the Disclosure Package and the Prospectus, are in full force and effect, and neither the Company nor any subsidiary has received notice of any material claim of any sort that has been asserted by anyone adverse to the rights of the Company or any subsidiary under any of the leases or subleases mentioned above, or affecting or questioning the rights of the Company or such subsidiary to the continued possession of the leased or subleased premises under any such lease or sublease.

(xxiii) Compliance with the Sarbanes-Oxley Act. There is, and has been, no failure on the part of the Company or, to the knowledge of the Company, any of the Company’s directors or officers, in their capacities as such, to comply with the provisions of the Sarbanes-Oxley Act of 2002 and the rules and regulations promulgated in connection therewith, except for such failures to comply that would not individually or in the aggregate reasonably be expected to have a Material Adverse Effect.

(xxiv) Internal Control Over Financial Reporting. Each of the Company and its subsidiaries maintains a system of internal control over financial reporting (as such term is defined in Rule 13a-15(f) under the Exchange Act) sufficient to provide reasonable assurance that (i) transactions are executed in accordance with management’s general or specific authorizations, (ii) transactions are recorded as necessary to permit preparation of financial statements in conformity with generally accepted accounting principles and to maintain accountability for assets, (iii) access to assets is permitted only in accordance with management’s general or specific authorization and (iv) the recorded accountability for assets is compared with the existing assets at reasonable intervals and appropriate action is taken with respect to any differences. The Company’s internal control over financial reporting is effective, and the Company is not aware of any material weaknesses in its internal control over financial reporting.

(xxv) Disclosure Control and Procedures. The Company maintains disclosure controls and procedures (as such term is defined in Rule 13a-15(e) under the Exchange Act) that comply with the requirements of the Exchange Act; and such disclosure controls and procedures have been designed to ensure that information required to be disclosed by the Company in the reports that it files or submits under the Exchange Act is communicated to the Company’s principal executive officer and principal financial officer by others within those entities to allow timely decisions regarding disclosure.

(b) Officers’ Certificates . Any certificate signed by any officer of the Company delivered to the Underwriters or to counsel for the Underwriters shall be deemed a representation and warranty by the Company, to each Underwriter as to the matters covered thereby on the date of such certificate and, unless subsequently amended or supplemented, at each Representation Date subsequent thereto.

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SECTION 2. Sale and Delivery to Underwriters; Closing

(a) Notes . On the basis of the representations and warranties herein contained and subject to the terms and conditions herein set forth, the Company agrees to sell to each Underwriter, severally and not jointly, and each Underwriter, severally and not jointly, agrees to purchase from the Company the principal amount of Notes set forth in Schedule A opposite the name of such Underwriter plus any additional principal amount which such Underwriter may be obligated to purchase pursuant to Section 11 hereto, at a price equal to 99.234% of the principal amount thereof, plus accrued interest, if any, from February 14, 2007.

(b) Delivery and Payment for the Notes . Delivery of the Notes shall be made at the offices of Sidley Austin LLP, 787 Seventh Ave, New York, New York 10019, at 10:00 A.M. New York City time, on February 14, 2007, or at such other pla