ASSIGNMENT, ASSUMPTION AND RECOGNITION AGREEMENT

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                                                                   EXHIBIT 99.12

                ASSIGNMENT, ASSUMPTION AND RECOGNITION AGREEMENT

     This is an Assignment, Assumption and Recognition Agreement (the
"Agreement") made this 1st day of September, 2006, among Merrill Lynch Mortgage
Lending, Inc., having an address at World Financial Center, South Tower, New
York, New York 10281 (the "Assignor"), Merrill Lynch Mortgage Investors, Inc.,
having an address at 4 World Financial Center, 10th Floor, New York, New York
10281 (the "Assignee") and CitiMortgage, Inc., having an address at 750
Washington Blvd., Stamford, Connecticut 06901 ("CitiMortgage").

     In consideration of the mutual promises contained herein the parties hereto
agree that the mortgage loans (the "Mortgage Loans") listed on Attachment 1
annexed hereto (the "Mortgage Loan Schedule") now serviced by CitiMortgage for
Assignor and its successors and assigns pursuant to the Mortgage Servicing
Purchase and Sale Agreement dated as of September 1, 2006, between Assignor and
CitiMortgage (the "Servicing Agreement") shall be subject to the terms of this
Agreement. Capitalized terms used herein but not defined shall have the meanings
ascribed to them in the Servicing Agreement.

                            ASSIGNMENT AND ASSUMPTION

     1. Assignor hereby grants, transfers and assigns to Assignee all of the
right, title and interest of Assignor in the Mortgage Loans and, to the extent
of the Mortgage Loans, all of its right, title and interest in, to and under the
Servicing Agreement.

         MODIFICATIONS OF CERTAIN PROVISIONS OF THE SERVICING AGREEMENT

     2. For purposes of servicing the Mortgage Loans hereunder, the parties
hereto agree that the provisions of the Servicing Agreement shall be modified in
the manner set forth on Exhibit A hereto.

                                   WARRANTIES

     3. Assignor warrants and represents to, and covenants with, the Assignee as
of the date hereof that:

     (a) Attached hereto as Attachment 2 is a true and accurate copy of the
Servicing Agreement which agreement is in full force and effect as of the date
hereof and the provisions of which have not been waived, amended or modified in
any respect, nor has any notice of termination been given thereunder;

     (b) Assignor is the lawful owner of the Mortgage Loans with full right to
transfer the Mortgage Loans and any and all of its interests, rights and
obligations under the Servicing Agreement to the extent of the Mortgage Loans
free and clear from any and all claims and encumbrances whatsoever and upon the
transfer of the Mortgage Loans to Assignee as contemplated herein, Assignee
shall have good title to each and every Mortgage Loan, as well as

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any and all of Assignee's interests, rights and obligations under the Servicing
Agreement to the extent of the Mortgage Loans, free and clear of all liens,
claims and encumbrances;

     (c) There are no offsets, counterclaims or other defenses available to
Assignor with respect to the Mortgage Loans or the Servicing Agreement;

     (d) Assignor has no knowledge of, and has not received notice of, any
waivers under, or any modification of, the Mortgage Loans;

     (e) Assignor is duly organized, validly existing and in good standing under
the laws of the jurisdiction of its incorporation, and has all requisite power
and authority to acquire, own and sell the Mortgage Loans;

     (f) Assignor has full corporate power and authority to execute, deliver and
perform its obligations under this Agreement, and to consummate the transactions
set forth herein. The consummation of the transactions contemplated by this
Agreement is in the ordinary course of Assignor's business and will not conflict
with, or result in a breach of, any of the terms, conditions or provisions of
Assignor's charter or by-laws or any legal restriction, or any material
agreement or instrument to which Assignor is now a party or by which it is
bound, or result in the violation of any law, rule, regulation, order, judgment
or decree to which Assignor or its property is subject. The execution, delivery
and performance by Assignor of this Agreement and the consummation by it of the
transactions contemplated hereby, have been duly authorized by all necessary
corporate action on part of Assignor. This Agreement has been duly executed and
delivered by Assignor and, upon the due authorization, execution and delivery by
Assignee and CitiMortgage, will constitute the valid and legally binding
obligation of Assignor enforceable against Assignor in accordance with its terms
except as enforceability may be limited by bankruptcy, reorganization,
insolvency, moratorium or other similar laws now or hereafter in effect relating
to creditors' rights generally, and by general principles of equity regardless
of whether enforceability is considered in a proceeding in equity or at law; and

     (g) No consent, approval, order or authorization of, or declaration, filing
or registration with, any governmental entity is required to be obtained or made
by Assignor in connection with the execution, delivery or performance by
Assignor of this Agreement, or the consummation by it of the transactions
contemplated hereby.

     4. Assignee warrants and represents to, and covenants with, Assignor and
CitiMortgage that as of the date hereof:

     (a) The Assignee is a corporation duly organized, validly existing and in
good standing under the laws of the jurisdiction of its incorporation, and has
all requisite corporate power and authority to acquire, own and purchase the
Mortgage Loans;

     (b) Assignee has full corporate power and authority to execute, deliver and
perform its obligations under this Agreement, and to consummate the transactions
set forth herein. The consummation of the transactions contemplated by this
Agreement is in the ordinary course of


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Assignee's business and will not conflict with, or result in a breach of, any of
the terms, conditions or provisions of Assignee's charter or by-laws or any
legal restriction, or any material agreement or instrument to which Assignee is
now a party or by which it is bound, or result in the violation of any law,
rule, regulation, order, judgment or decree to which Assignee or its property is
subject. The execution, delivery and performance by Assignee of this Agreement
and the consummation by it of the transactions contemplated hereby, have been
duly authorized by all necessary corporate action on part of Assignee. This
Agreement has been duly executed and delivered by Assignee and, upon the due
authorization, execution and delivery by Assignor and CitiMortgage, will
constitute the valid and legally binding obligation of Assignee enforceable
against Assignee in accordance with its terms except as enforceability may be
limited by bankruptcy, reorganization, insolvency, moratorium or other similar
laws now or hereafter in effect relating to creditors' rights generally, and by
general principles of equity regardless of whether enforceability is considered
in a proceeding in equity or at law;

     (c) No consent, approval, order or authorization of, or declaration, filing
or registration with, any governmental entity is required to be obtained or made
by Assignee in connection with the execution, delivery or performance by
Assignee of this Agreement, or the consummation by it of the transactions
contemplated hereby; and

     (d) Assignee agrees to be bound, as "Seller" (as such term is defined under
the Servicing Agreement), by all of the terms, covenants and conditions of the
Servicing Agreement and the Mortgage Loans, and from and after the date hereof,
the Assignee assumes for the benefit of each of Assignor and CitiMortgage all of
Assignor's obligations as Seller thereunder.

     5. CitiMortgage warrants and represents to, and covenants with, Assignor
and Assignee that as of the date hereof:

     (a) CitiMortgage is a corporation duly organized, validly existing and in
good standing under the laws of the jurisdiction of its incorporation;

     (b) CitiMortgage has full corporate power and authority to execute, deliver
and perform its obligations under this Agreement, and to consummate the
transactions set forth herein. The consummation of the transactions contemplated
by this Agreement is in the ordinary course of CitiMortgage's business and will
not conflict with, or result in a breach of, any of the terms, conditions or
provisions of CitiMortgage's charter or by-laws or any legal restriction, or any
material agreement or instrument to which CitiMortgage is now a party or by
which it is bound, or result in the violation of any law, rule, regulation,
order, judgment or decree to which CitiMortgage or its property is subject. The
execution, delivery and performance by CitiMortgage of this Agreement and the
consummation by it of the transactions contemplated hereby, have been duly
authorized by all necessary corporate action on part of CitiMortgage. This
Agreement has been duly executed and delivered by CitiMortgage and, upon the due
authorization, execution and delivery by Assignor and Assignee, will constitute
the valid and legally binding obligation of CitiMortgage enforceable against
CitiMortgage in accordance with its terms except as enforceability may be
limited by bankruptcy, reorganization, insolvency, moratorium or other similar
laws now or hereafter in effect relating to creditors' rights generally,


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and by general principles of equity regardless of whether enforceability is
considered in a proceeding in equity or at law; and

     (c) No consent, approval, order or authorization of, or declaration, filing
or registration with, any governmental entity is required to be obtained or made
by CitiMortgage in connection with the execution, delivery or performance by
CitiMortgage of this Agreement, or the consummation by it of the transactions
contemplated hereby.

                             RECOGNITION OF ASSIGNEE

     6. From and after the date hereof, CitiMortgage shall recognize Assignee as
owner of the Mortgage Loans and will service the Mortgage Loans in accordance
with the Servicing Agreement, as if Assignee and CitiMortgage had entered into a
separate servicing agreement for the servicing of the Mortgage Loans in the form
of the Servicing Agreement, the terms of which are incorporated herein by
reference. It is the intention of Assignor, CitiMortgage and Assignee that the
Agreement will constitute a separate and distinct servicing agreement, and the
entire agreement, between CitiMortgage and Assignee to the extent of the
Mortgage Loans and shall be binding upon and for the benefit of the respective
successors and assigns of the parties hereto.

     7. The Mortgage Loans shall be serviced by CitiMortgage for Assignee in
accordance with all applicable state, federal and local laws as well as in
conformity with the provisions of the applicable Mortgages and Mortgage Notes,
and pursuant to the terms and conditions of this Agreement.

     8. CitiMortgage acknowledges that Wells Fargo Bank, N.A. (the "Master
Servicer" and "Securities Administrator") has been appointed as the master
servicer of the Assigned Loans pursuant to the Pooling and Servicing Agreement,
dated as of September 1, 2006, by and among the Assignee, the Master Servicer,
the Securities Administrator and HSBC Bank USA, National Association (the
"Pooling and Servicing Agreement"). CitiMortgage shall deliver all reports
required to be delivered under the Servicing Agreement to:

          Wells Fargo Bank, N.A.
          9062 Old Annapolis Road
          Columbia, Maryland 21045
          Attention: Merrill Lynch Mortgage Investors, Inc., Series 2006-AF1

     9. CitiMortgage hereby acknowledges that the Master Servicer has the right
to enforce all obligations of CitiMortgage under the Servicing Agreement acting
on behalf of the Assignee, as owner of the Assigned Loans. Such rights will
include, without limitation, the right to terminate CitiMortgage, as purchaser
under the Servicing Agreement upon the occurrence of an event of default
thereunder, the right to receive all remittances required to be made by
CitiMortgage under the Servicing Agreement, the right to receive all monthly
reports and other data required to be delivered by CitiMortgage under the
Servicing Agreement, the right to


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examine the books and records of CitiMortgage and the right to exercise certain
rights of consent and approval of the "Seller" under the Servicing Agreement.
Notwithstanding the foregoing, it is understood that CitiMortgage shall not be
obligated to defend and indemnify and hold harmless the Master Servicer, the
Assignee and the Assignor from and against any losses, damages, penalties,
fines, forfeitures, judgments and any related costs including, without
limitation, reasonable and necessary legal fees, resulting from (i) actions or
inactions of CitiMortgage which were taken or omitted upon the instruction or
direction of the Master Servicer or (ii) the failure of the Master Servicer to
perform the obligations of the "Seller" under the Servicing Agreement and this
Agreement only to the extent that the Master Servicer has any obligations of the
"Seller". In addition, the Assignee shall indemnify CitiMortgage and hold it
harmless against any and all claims, losses, damages, penalties, fines,
forfeitures, reasonable and necessary legal fees and related costs, judgments,
and any other costs, fees and expenses that CitiMortgage may sustain in any way
related to (a) actions or inactions of CitiMortgage which were taken or omitted
upon the instruction or direction of the Trustee or Master Servicer, as
applicable, or (b) the failure of the Trustee or the Master Servicer, as
applicable, to perform the obligations of the "Seller" under the Servicing
Agreement and this Agreement. CitiMortgage shall make all distributions under
the Servicing Agreement to the Master Servicer by wire transfer of immediately
available funds to:

          Wells Fargo Bank, N.A.
          ABA Number: #121-000-248
          Account Name: Corporate Trust Clearing
          Account number: 3970771416
          For further credit to: MLMI 2006-AF1
          Distribution Account Number: 50948000

     10. For purposes of both Section L and Section AA of Exhibit M of the
Servicing Agreement, CitiMortgage is hereby notified, and CitiMortgage hereby
acknowledges receipt of such notification, that a REMIC election has been made
with respect to the Assigned Loans.

                                  MISCELLANEOUS

     11. All demands, notices and communications related to the Mortgage Loans,
the Servicing Agreement and this Agreement shall be in writing and shall be
deemed to have been duly given if personally delivered at or mailed by
registered mail, postage prepaid, as follows:

     (a)  In the case of CitiMortgage,

          CitiMortgage, Inc.
          1000 Technology Drive, MS 55,
          O'Fallon, Missouri 63368
          Attention: Capital Markets

          with a copy to


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          Investor Reporting Department, MS 314

     (b)  In the case of Assignee,

          Merrill Lynch Mortgage Investors, Inc.
          4 World Financial Center, 10th Floor
          New York, New York 10281
          Attention: MLMI 2006-AF1

     (c)  In the case of Assignor,

          Merrill Lynch Mortgage Lending, Inc.
          4 World Financial Center, South Tower
          New York, New York 10281
          Attention: MLMI 2006-AF1

     12. This Agreement shall be construed in accordance with the laws of the
State of New York, except to the extent preempted by Federal law, and the
obligations, rights and remedies of the parties hereunder shall be determined in
accordance with such laws.

     13. No term or provision of this Agreement may be waived or modified unless
such waiver or modification is in writing and signed by the party against whom
such waiver or modification is sought to be enforced.

     14. This Agreement shall inure to the benefit of the successors and assigns
of the parties hereto. Any entity into which the Assignor, Assignee or
CitiMortgage may be merged or consolidated shall, without the requirement for
any further writing, be deemed the Assignor, Assignee or CitiMortgage,
respectively, hereunder.

     15. This Agreement shall survive the conveyance of the Mortgage Loans, the
assignment of the Servicing Agreement to the extent of the Mortgage Loans by the
Assignor to the Assignee and the termination of the Servicing Agreement.

     16. This Agreement shall terminate upon a clean up call of the Merrill
Lynch Mortgage Investors Trust, Series 2006-AF1; provided, however, that the
Servicer shall continue to service the Mortgage Loans subject to such clean up
call pursuant to the Servicing Agreement.

     17. This Agreement may be executed simultaneously in any number of
counterparts. Each counterpart shall be deemed to be an original, and all such
counterparts shall constitute one and the same instrument.


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     IN WITNESS WHEREOF, the parties hereto have executed this Agreement the day
and year first above written.

MERRILL LYNCH MORTGAGE LENDING, INC.
Assignor


By:
    ---------------------------------
Name:
      -------------------------------
Title:
       ------------------------------


MERRILL LYNCH MORTGAGE INVESTORS, INC.
Assignee


By:
    ---------------------------------
Name:
      -------------------------------
Title:
       ------------------------------


CITIMORTGAGE, INC.
Company


By:
    ---------------------------------
Name:
      -------------------------------
Title:
       ------------------------------


ACKNOWLEDGED AND AGREED:

WELLS FARGO BANK, N.A.
Master Servicer


By:
    ---------------------------------
Name:
      -------------------------------
Title:
       ------------------------------

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                                  ATTACHMENT 1

                             MORTGAGE LOAN SCHEDULE

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                                  ATTACHMENT 2

                 MORTGAGE SERVICING PURCHASE AND SALE AGREEMENT

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                                    Exhibit A

                    Modifications to the Servicing Agreement

1.   The third paragraph of Section 12.01 is hereby modified by the insertion of
     the word "with" following the words "shall cooperate" and by the deletion
     of the words "notice of".

2.   Section 12.03(e) is hereby modified by the insertion of the words ", any
     Master Servicer" immediately following the words "(x) written notice to the
     Seller".

3.   Section 12.03(g) is hereby modified by the insertion of the words "copies
     or other evidence of fidelity bond insurance and errors and omissions
     insurance," immediately following the words "the person signing any
     certification or statement,".

4.   Section 12.04 is hereby modified by the insertion of the words "in the case
     of the Depositor," before the words "upon request".

5.   Section 12.05(a)(i) is hereby modified by the insertion of the words "in
     the case of the Depositor," before the words "upon request" within the
     parenthetical.

6.   Section 12.05(a)(ii) is hereby modified by the insertion of the words "in
     the case of the Depositor," before the words "upon request" within the
     parenthetical.

7.   Section 12.05(a)(iii) is hereby modified by replacing the word "and"
     following the words "Regulation AB," with the words "to deliver" and by the
     insertion of the word "and" immediately following the words "Section
     12.04,".

8.   Section 12.05(a)(iv) is hereby modified by the deletion of the words "if
     requested by any Depositor or any Master Servicer not later than March 1 of
     the calendar year in which such certification is to be delivered," and by
     the insertion of the words "(in the case of the Depositor, solely if
     requested prior to March 1 of the calendar year in which such certification
     is to be delivered).

9.   Exhibit M is hereby modified by replacing the first paragraph of Section
     (N) with the following paragraph:


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     On or before the fifth (5th) Business Day of each month, the Purchaser
     shall furnish to the Seller or its designee, in mutually agreeable
     electronic format and as to the latest Due Period, the information included
     in the delinquency report set forth in Exhibit M-1, the monthly remittance
     advice set forth in Exhibit M-2, and the realized loss report set forth in
     Exhibit M-3 (provided that the information to be provided in each case may
     be either in the form set forth in the applicable exhibit or in such other
     form as the parties shall agree or have previously agreed upon), together
     with such other information with respect to the Mortgage Loans as the
     Seller may reasonably require to allocate distributions made pursuant to
     this Agreement and to provide appropriate statements in connection
     therewith.

10.  Exhibit M is hereby modified by the deletion of sections (S) and (T) and
     Subsection (i) of Section (W).

11.  Exhibit M is hereby modified by the deletion, from paragraph (b) of Section
     (Y), the words "without cause, including without limitation upon exercise
     of any clean up call with respect to a Reconstitution" and by the insertion
     in such paragraph, immediately following the words "with respect to the
     Servicing so terminated" the words "; provided, no such termination fee
     shall be payable in any case of termination for cause or termination
     pursuant to the exercise of any clean up call with respect to a
     Reconstitution".

12.  Exhibit M-1 is hereby modified by replacing such exhibit in its entirety
     with Exhibit B-1 to this Assignment, Assumption and Recognition Agreement.

13.  Exhibit M-2 is hereby modified by replacing such exhibit in its entirety
     with Exhibit B-2 to this Assignment, Assumption and Recognition Agreement.

14.  The Servicing Agreement is hereby modified by the addition of a new Exhibit
     M-3, which shall be identical to Exhibit B-3 to this Assignment, Assumption
     and Recognition Agreement


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                                   Exhibit B-1

                                 Monthly Report

<TABLE>
<CAPTION>
                                                                                                                               MAX
COLUMN NAME              DESCRIPTION                                           DECIMAL   FORMAT COMMENT                       SIZE
-----------              -----------                                           -------   --------------                       ----
<S>                      <C>                                                   <C>       <C>                                  <C>
SER_INVESTOR_NBR         A value assigned by the Servicer to define a group              Text up to 10 digits                   20
                         of loans.

LOAN_NBR                 A unique identifier assigned to each loan by the                Text up to 10 digits                   10
                         investor.

SERVICER_LOAN_NBR        A unique number assigned to a loan by the                       Text up to 10 digits                   10
                         Servicer. This may be different than the LOAN_NBR.

BORROWER_NAME            The borrower name as received in the file. It is               Maximum length of 30 (Last, First)      30
                         not separated by first and last name.

SCHED_PAY_AMT            Scheduled monthly principal and scheduled interest       2      No commas(,) or dollar signs ($)       11
                         payment that a borrower is expected to pay, P&I
                         constant.

NOTE_INT_RATE            The loan interest ra