ASSIGNMENT, ASSUMPTION AND RECOGNITION AGREEMENT

Exhibit 99.15(a)

EXECUTION COPY



ASSIGNMENT, ASSUMPTION AND RECOGNITION AGREEMENT

THIS ASSIGNMENT, ASSUMPTION AND RECOGNITION AGREEMENT (this
"Assignment"), dated as of February 1, 2006, is entered into among Morgan
Stanley Capital I Inc., a Delaware corporation (the "Depositor"), Morgan
Stanley Mortgage Capital Inc. ("MSMCI"), Wachovia Mortgage Corporation as
seller ("Wachovia" and, in such capacity, the "Seller") and servicer (in such
capacity, the "Servicer"), and acknowledged by LaSalle Bank National
Association, as trustee (the "Trustee") of Morgan Stanley Mortgage Loan Trust
2006-3AR (the "Trust"), and Wells Fargo Bank, National Association, as master
servicer (or any successor master servicer, the "Master Servicer").

RECITALS

WHEREAS MSMCI, the Seller and the Servicer have entered into a certain
Seller's Purchase, Warranties and Servicing Agreement, dated as of September
1, 2004 (the "Initial Agreement"), as supplemented by the Regulation AB
Compliance Addendum (the "Reg AB Addendum"), dated as of November 22, 2005,
(as further amended or modified to the date hereof, the "Agreement"), pursuant
to which MSMCI has acquired certain Mortgage Loans pursuant to the terms of
the Agreement and the Servicer has agreed to service such Mortgage Loans;

WHEREAS the Depositor has agreed, on the terms and conditions contained
herein, to purchase from MSMCI certain of the Mortgage Loans (the "Specified
Mortgage Loans") which are subject to the provisions of the Agreement and are
listed on the mortgage loan schedule attached as Exhibit I hereto (the
"Specified Mortgage Loan Schedule"); and

WHEREAS the Trustee, on behalf of the Trust, has agreed, on the terms
and conditions contained herein, to purchase from the Depositor the Specified
Mortgage Loans;

NOW, THEREFORE, in consideration of the mutual promises contained herein
and other good and valuable consideration (the receipt and sufficiency of
which are hereby acknowledged), the parties agree as follows:

1. Assignment and Assumption
-------------------------

(a) On and as of the date hereof, MSMCI hereby sells, assigns and
transfers to the Depositor all of its right, title and interest in the
Specified Mortgage Loans and all rights and obligations related thereto as
provided under the Agreement to the extent relating to the Specified Mortgage
Loans, the Depositor hereby accepts such assignment from MSMCI (the "First
Assignment and Assumption"), and the Seller hereby acknowledges the First
Assignment and Assumption.

MSMCI specifically reserves and does not assign to the Depositor
hereunder any and all right, title and interest in, to and under and all
obligations of MSMCI with respect to any Mortgage Loans subject to the
Agreement which are not the Specified Mortgage Loans.

(b) On and as of the date hereof, immediately after giving effect to the
First Assignment and Assumption, the Depositor hereby sells, assigns and
transfers to the Trustee, on behalf of the Trust, all of its right, title and
interest in the Specified Mortgage Loans and all rights and obligations
related thereto as provided under the Agreement to the extent relating to the
Specified Mortgage Loans, and the Trustee, on behalf of the Trust, hereby
accepts such assignment from the Depositor (the "Second Assignment and
Assumption"), and the Seller hereby acknowledges the Second Assignment and
Assumption.

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(c) On and as of the date hereof, MSMCI represents and warrants to the
Depositor and the Trustee that MSMCI has not taken any action that would serve
to impair or encumber the respective ownership interests of the Depositor and
the Trustee in the Specified Mortgage Loans since the date of MSMCI's
acquisition of the Specified Mortgage Loans.

2. Recognition of Trustee
----------------------

(a) From and after the date hereof, both MSMCI and the Seller shall note
the transfer of the Specified Mortgage Loans to the Trustee, in their
respective books and records and shall recognize the Trustee, on behalf of the
Trust, as of the date hereof, as the owner of the Specified Mortgage Loans,
and Servicer shall service the Specified Mortgage Loans for the benefit of the
Trust pursuant to the Agreement, as modified hereby, the terms of which are
incorporated herein by reference. It is the intention of the Seller, the
Servicer, the Depositor, the Trustee and MSMCI that this Assignment shall be
binding upon and inure to the benefit of the Depositor, the Trustee and MSMCI
and their respective successors and assigns.

(b) Without in any way limiting the foregoing, the parties confirm that
this Assignment includes the rights relating to amendments or waivers under
the Agreement. Accordingly, the right of MSMCI to consent to any amendment of
the Agreement and its rights concerning waivers as set forth in Sections 11.02
and 8.02 of the Agreement shall be exercisable, to the extent any such
amendment or waiver affects the Specified Mortgage Loans or any of the rights
under the Agreement with respect thereto (other than the servicing of the
Specified Mortgage Loans, which shall be enforced by the Master Servicer) by
the Trustee as assignee of MSMCI.

(c) It is expressly understood and agreed by the parties hereto that (i)
this Assignment is executed and delivered by LaSalle Bank National
Association, not individually or personally but solely on behalf of the Trust,
as the assignee, in the exercise of the powers and authority conferred and
vested in it, as Trustee, pursuant to the Pooling and Servicing Agreement
dated as of the date hereof among the Depositor, the Master Servicer, Wells
Fargo Bank, National Association, as securities administrator (the "Securities
Administrator") and the Trustee (the "Pooling and Servicing Agreement"), (ii)
each of the representations, undertakings and agreements herein made on the
part of assignee is made and intended not as personal representations,
undertakings and agreements by LaSalle Bank National Association but is made
and intended for the purpose of binding only the Trust , (iii) nothing herein
contained shall be construed as creating any liability for LaSalle Bank
National Association, individually or personally, to perform any covenant
(either express or implied) contained herein and (iv) under no circumstances
shall LaSalle Bank National Association be personally liable for the payment
of any indebtedness or expenses of the Trust, or be liable for the breach or
failure of any obligation, representation, warranty or covenant made or
undertaken by the Trust under this Assignment and (v) all recourse for any
payment liability or other obligation of the assignee shall be had solely to
the assets of the Trust.

3. Representations and Warranties
------------------------------

(a) The Depositor represents and warrants that it is a sophisticated
investor able to evaluate the risks and merits of the transactions
contemplated hereby, and that it has not relied in connection therewith upon
any statements or representations of the Seller or MSMCI other than those
contained in the Agreement or this Assignment.

(b) Each of the parties hereto represents and warrants that it is duly
and legally authorized to enter into this Assignment.


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(c) Each of the Depositor, MSMCI, Seller and Servicer hereto represents
and warrants that this Assignment has been duly authorized, executed and
delivered by it and (assuming due authorization, execution and delivery
thereof by each of the other parties hereto) constitutes its legal, valid and
binding obligation, enforceable against it in accordance with its terms,
except as such enforcement may be limited by bankruptcy, insolvency,
reorganization or other similar laws affecting the enforcement of creditors'
rights generally and by general equitable principles (regardless of whether
such enforcement is considered in a proceeding in equity or at law).

(d) The Seller hereby makes, as of the Closing Date (as defined in the
Pooling and Servicing Agreement referred to below), the representations and
warranties set forth in Section 3.01 of the Agreement, to and for the benefit
of the Depositor, the Trustee and the Trust, and by this reference
incorporates such representations and warranties herein, as of such Closing
Date.

4. The Servicer hereby acknowledges that Wells Fargo Bank, National
Association has been appointed as the Master Servicer of the Specified
Mortgage Loans pursuant to the Pooling and Servicing Agreement and, therefore,
has the right to enforce all obligations of the Servicer under the Agreement.
Such rights will include, without limitation, the right to terminate the
Servicer under the Agreement upon the occurrence of an event of default
thereunder, the right to receive all remittances required to be made by the
Servicer under the Agreement, the right to receive all monthly reports and
other data required to be delivered by the Servicer under the Agreement, the
right to examine the books and records of the Servicer, indemnification rights
and the right to exercise certain rights of consent and approval of MSMCI. The
Servicer shall make all distributions under the Agreement to the Master
Servicer by wire transfer of immediately available funds to:

Wells Fargo Bank, National Association
ABA Number: 121-000-248
Account Name: Corporate Trust Clearing
Account number: 3970771416
For further credit to: 50896100, MSM 2006-3AR

The Servicer shall deliver all reports required to be delivered under
the Agreement to the Master Servicer at the following address:

Wells Fargo Bank, National Association
9062 Old Annapolis Road
Columbia, Maryland 21045
Attention: Client Manager, MSM 2006-3AR
Telecopier: (410) 715-2380

5. Amendments to the Initial Agreement
-----------------------------------

The parties to this Assignment hereby agree to amend the Initial
Agreement as follows:

(a) With respect to the Specified Mortgage Loans, "Permitted
Investments" shall mean at any time, any one or more of the
following obligations and securities:

(i) obligations of the United States or any agency thereof,
provided that such obligations are backed by the full faith
and credit of the United States;

(ii) general obligations of or obligations guaranteed by any
state of the United States or the District of Columbia
receiving the highest long-term debt rating of

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each Rating Agency, or such lower rating as shall not result
in the downgrading or withdrawal of the ratings then
assigned to the Certificates by the Rating Agencies, as
evidenced by a signed writing delivered by each Rating
Agency;

(iii) commercial or finance company paper which is then
receiving the highest commercial or finance company paper
rating of each Rating Agency rating such paper, or such
lower rating as shall not result in the downgrading or
withdrawal of the ratings then assigned to the Certificates
by the Rating Agencies, as evidenced by a signed writing
delivered by each Rating Agency;

(iv) certificates of deposit, demand or time deposits, or
bankers' acceptances issued by any depository institution or
trust company incorporated under the laws of the United
States or of any state thereof and subject to supervision
and examination by federal and/or state banking authorities,
provided that the commercial paper and/or long-term
unsecured debt obligations of such depository institution or
trust company (or in the case of the principal depository
institution in a holding company system, the commercial
paper or long-term unsecured debt obligations of such
holding company, but only if Moody's is not the applicable
Rating Agency) are then rated one of the two highest
long-term and the highest short-term ratings of each Rating
Agency for such securities, or such lower ratings as shall
not result in the downgrading or withdrawal of the ratings
then assigned to the Certificates by the Rating Agencies, as
evidenced by a signed writing delivered by each Rating
Agency;

(v) demand or time deposits or certificates of deposit
issued by any bank or trust company or savings institution
to the extent that such deposits are fully insured by the
FDIC;

(vi) guaranteed reinvestment agreements issued by any bank,
insurance company or other corporation acceptable to the
Rating Agencies at the time of the issuance of such
agreements, as evidenced by a signed writing delivered by
each Rating Agency;

(vii) repurchase obligations with respect to any security
described in clauses (i) and (ii) above, in either case
entered into with a depository institution or trust company
(acting as principal) described in clause (iv) above;

(viii) securities (other than stripped bonds, stripped
coupons or instruments sold at a purchase price in excess of
115% of the face amount thereof) bearing interest or sold at
a discount issued by any corporation incorporated under the
laws of the United States or any state thereof which, at the
time of such investment, have one of the two highest ratings
of each Rating Agency (except if the Rating Agency is
Moody's, such rating shall be the highest commercial paper
rating of Moody's for any such series), or such lower rating
as shall not result in the downgrading or withdrawal of the
ratings then assigned to the Certificates by the Rating
Agencies, as evidenced by a signed writing delivered by each
Rating Agency;

(ix) interests in any money market fund which at the date of
acquisition of the interests in such fund and throughout the
time such interests are held in such fund has the highest
applicable rating by each Rating Agency rating such fund or
such

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lower rating as shall not result in a change in the rating
then assigned to the Certificates by each Rating Agency, as
evidenced by a signed writing delivered by each Rating
Agency, including funds for which the Trustee, the Master
Servicer, the Securities Administrator or any of its
Affiliates is investment manager or adviser;

(x) short-term investment funds sponsored by any trust
company or national banking association incorporated under
the laws of the United States or any state thereof which on
the date of acquisition has been rated by each applicable
Rating Agency in their respective highest applicable rating
category or such lower rating as shall not result in a
change in the rating then specified stated maturity and
bearing interest or sold at a discount acceptable to each
Rating Agency as shall not result in the downgrading or
withdrawal of the ratings then assigned to the Certificates
by the Rating Agencies, as evidenced by a signed writing
delivered by each Rating Agency; and

(xi) such other investments having a specified stated
maturity and bearing interest or sold at a discount
acceptable to the Rating Agencies as shall not result in the
downgrading or withdrawal of the ratings then assigned to
the Certificates by the Rating Agencies, as evidenced by a
signed writing delivered by each Rating Agency;

provided, that no such instrument shall be a Permitted
Investment if (i) such instrument evidences the right to
receive interest only payments with respect to the
obligations underlying such instrument or (ii) such
instrument would require the Depositor to register as an
investment company under the Investment Company Act of 1940,
as amended.

(b) The definition of "Remittance Date" in Section 1.01 of the
Initial Agreement is hereby amended and restated in its entirety
as follows:

"Remittance Date: The 18th day of each month (or, if such 18th day is
not a Business Day, the following Business Day)."

(c) The definition of "Servicing Fee" in Section 1.01 of the
Initial Agreement is hereby amended and restated in its entirety
as follows:

"The Servicing Fee with respect to each Mortgage Loan for any calendar
month (or a portion thereof) shall be 1/12 of the product of (i) the Scheduled
Principal Balance of the Mortgage Loan and (ii) the Servicing Fee Rate
applicable to such Mortgage Loan. Such fee shall be payable monthly, computed
on the basis of the same principal amount and period respecting which any
related interest payment on a Mortgage Loan is computed."

(d) The definition of "Servicing Fee Rate" in Section 1.01 of the
Initial Agreement is hereby amended and restated in its entirety
as follows:

"Servicing Fee Rate": With respect to the adjustable rate Mortgage
Loans, 0.250% per annum."

(e) Subsection 3.02(d) of the Initial Agreement is hereby amended
and restated in its entirety as follows:

"As of the Closing Date, none of the Mortgage Loans are contractually
past due by more than 30 days;"

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(f) The following paragraphs are hereby incorporated into the
Initial Agreement at the end of Section 4.13:

"The Seller shall prepare for and deliver to the Purchaser, or its
designee, a statement with respect to each REO Property that has been rented
showing the aggregate rental income received and all expenses incurred in
connection with the maintenance of such REO Property at such times as is
necessary to enable the Purchaser, or its designee, to comply with the
reporting requirements of the REMIC Provisions. The net monthly rental income,
if any, from such REO Property shall be deposited in the Certificate Account
no later than the close of business on each Determination Date. The Seller
shall perform the tax reporting and withholding required by Sections 1445 and
6050J of the Code with respect to foreclosures and abandonments, the tax
reporting required by Section 6050H of the Code with respect to the receipt of
mortgage interest from individuals and any tax reporting required by Section
6050P of the Code with respect to the cancellation of indebtedness by certain
financial entities, by preparing such tax and information returns as may be
required, in the form required, and delivering the same to the Purchaser, or
its designee, for filing.

Notwithstanding any other provision of this Agreement, no Mortgaged
Property acquired by the Purchaser, or its designee, shall be rented (or
allowed to continue to be rented) or otherwise used for the production of
income by or on behalf of the Purchaser, or its designee, in such a manner or
pursuant to any terms that would (i) cause such Mortgaged Property to fail to
qualify as "foreclosure property" within the meaning of section 860G(a)(8) of
the Code or (ii) subject any REMIC to the imposition of any federal, state or
local income taxes on the income earned from such Mortgaged Property under
Section 860G(c) of the Code or otherwise, unless the Seller has agreed to
indemnify and hold harmless the Purchaser, or its designee, with respect to
the imposition of any such taxes."

(g) The second paragraph of Section 5.01 of the Initial Agreement
is hereby amended and restated in its entirety as follows:

"With respect to any remittance received by the Purchaser after the
Business Day on which such payment was due, the Seller shall pay to the
Purchaser interest on any such late payment at an annual rate equal to the
Prime Rate, adjusted as of the date of each change, plus two percentage
points, but in no event greater than the maximum amount permitted by
applicable law. Such interest shall be deposited in the Custodial Account by
the Seller on the date such late payment is made and shall cover the period
commencing with such Business Day on which such payment was due and ending
with the Business Day on which such payment is made, both inclusive. Such
interest shall be remitted along with the distribution payable on the next
succeeding Remittance Date. The payment by the Seller of any such interest
shall not be deemed an extension of time for payment or a waiver of any Event
of Default by the Seller."

(h) The first paragraph of Section 5.02 of the Initial Agreement
is hereby amended and restated in its entirety as follows:

"Not later than the 5th Business Day of each month (or if such 5th day
is not a Business Day, the Business Day next succeeding such 5th day), the
Seller shall furnish to the Master Servicer in electronic form mortgage loan
level data as mutually agreed upon by the Seller and the Master Servicer and
the monthly reports substantially in the form of Exhibit J attached hereto
with respect to the Mortgage Loans and the period from but including the first
day of the preceding calendar month through but excluding the first day of
such month."

(i) The first paragraph of Section 5.03 of the Initial Agreement
is hereby amended and restated in its entirety as follows:

"Not later than the close of business on the Business Day preceding each
Remittance Date, the Seller shall either (a) deposit in the Custodial Account
from its own funds an amount equal to the



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principal and interest portion of all Monthly Payments (with interest adjusted
to the Mortgage Loan Remittance Rate) which were due on the Mortgage Loans
during the applicable Due Period and which were delinquent at the close of
business on the immediately preceding Determination Date or which were
deferred pursuant to Section 4.01, (b) cause to be made an appropriate entry
in the records of the Custodial Account that amounts held for future
distribution have been, as permitted by this Section 5.03, used by the Seller
in discharge of any such Monthly Advance or (c) make Monthly Advances in the
form of any combination of (a) or (b) aggregating the total amount of Monthly
Advances to be made, whether or not deferred pursuant to Section 4.01, which
were due on a Mortgage Loan on the immediately preceding Due Date and
delinquent at the close of business on the related Determination Date."

(j) The word "or" is deleted from the end of Section 8.01(vii),
the word "or" is added at the end of Section 8.01(viii) and the
following paragraph is hereby incorporated into the Agreement as
new Section 10.01(ix):

"(ix) failure by the Seller to duly perform, within the required time
period, its obligations under Section 2.04 and Section 2.05 of the Reg AB
Addendum which failure continues unremedied for a period of fourteen (14) days
after the date on which written notice of such failure, requiring the same to
be remedied, shall have been given to the Seller by any party to this
Agreement or by any master servicer responsible for master servicing the
Mortgage Loans pursuant to a securitization of such Mortgage Loans;"

(k) The following paragraph is hereby incorporated into the
Initial Agreement as new Section 11.19:

"Third Party Beneficiary. For purposes of this Agreement, including but
not limited to Section 2.04 and Section 2.05, respectively, of the Reg AB
Addendum, any Master Servicer shall be considered a third party beneficiary to
this Agreement (including the Reg AB Addendum and any other amendments or
modifications thereto) entitled to all the rights and benefits accruing to any
Master Servicer herein as if it were a direct party to this Agreement."

(l) Section 6.04 and Section 6.05 are hereby deleted from the
Initial Agreement, it being understood that they are superseded by
Section 2.04 and Section 2.05, respectively, of the Reg AB
Addendum.

(m) The second sentence in Section 8.01 of the Initial Agreement
is hereby replaced by the following:

"On or after the receipt by the Seller of such written notice of
termination, all authority and power of the Seller, as servicer, under this
Agreement, whether with respect to the Mortgage Loans or otherwise, shall pass
to and be vested in the successor appointed pursuant to Section 11.01."

(n) Exhibit J to the Initial Agreement is hereby replaced in its
entirety with the Amended and Restated Exhibit J attached to this
Assignment as Exhibit II.

6. Amendments to the Reg AB Addendum
---------------------------------

(a) The following is added as new defined terms in Article I of the
Reg AB Addendum:

Indemnified Party: each Party described in the first sentence of Section
2.07(a) hereof.

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(b) The words "for a period" are hereby deleted from and the reference
to "Securitization Transfer" is revised to read "Securitization
Transaction" in each case in the second paragraph of Section
2.01(a) of the Reg AB Addendum.

(c) Section 2.03(d) of the Reg AB Addendum is hereby amended and
restated in its entirety as follows:

"For the purpose of satisfying its reporting obligation under the
Exchange Act with respect to any class of asset-backed securities, the Company
shall (or shall cause each Subservicer and Third-Party Originator to) (i)
promptly notify the Purchaser and any Depositor in writing of (A) any
litigation or governmental proceedings pending against the Company, any
Subservicer or any Third-Party Originator that would be material to
securityholders, (B) any affiliations or relationships that develop following
the closing date of a Securitization Transaction between the Company, any
Subservicer or any Third-Party Originator and any of the parties specified in
clause (D) of paragraph (a) of this Section (and any other parties identified
in writing by the requesting party) with respect to such Securitization
Transaction, but only to the extent that such affiliations or relationships do
not include the Purchaser, Depositor or any of their respective affiliates as
a party, (C) any Event of Default under the terms of the Agreement or any
Reconstitution Agreement, and (D) any sale of substantially all of the assets
of the Company and (E) the Company's entry into an agreement with a
Subcontractor to perform or assist the Company with the performance of any of
the Company's obligations under the Agreement, and (ii) provide to the
Purchaser and any Depositor a description of such proceedings, affiliations or
relationships."

(d) Section 2.03(f) of the Reg AB Addendum is hereby amended and
restated in its entirety as follows:

"In addition to such information as the Company, as servicer, is
obligated to provide pursuant to other provisions of the Agreement, not later
than