SecProbe.io

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Mail Stop 3651

      December 20, 2005

Via U.S. Mail

Edmund Taylor
Credit Suisse First Boston Mortgage Securities Corp.
11 Madison Avenue
New York, New York 10010

Re:  	Credit Suisse First Boston Mortgage Securities Corp.
	Registration Statement on Form S-3
Filed November 23, 2005
	File No. 333-129918

Dear Mr. Taylor:

      We have limited our review of your filing for compliance
with
Regulation AB.  Please further note that our limited review only
covers the issues that we have addressed in our comments.  Where
indicated, we think you should revise your document in response to
these comments.  If you disagree, we will consider your
explanation
as to why our comment is inapplicable or a revision is
unnecessary.
Please be as detailed as necessary in your explanation.  In some
of
our comments, we may ask you to provide us with supplemental
information so we may better understand your disclosure.  After
reviewing this information, we may or may not raise additional
comments.

	Please understand that the purpose of our review process is
to
assist you in your compliance with the applicable disclosure
requirements and to enhance the overall disclosure in your filing.
We look forward to working with you in these respects.  We welcome
any questions you may have about our comments or on any other
aspect
of our review.  Feel free to call us at the telephone numbers
listed
at the end of this letter.

General

1. Please confirm that the depositor or any issuing entity
previously
established, directly or indirectly, by the depositor or any
affiliate of the depositor has been current with Exchange Act
reporting during the last twelve months with respect to asset-
backed
securities involving the same asset class.  Please refer to
General
Instruction I.A.4. of Form S-3.  Also, please provide us with the
CIK
codes for any affiliate of the depositor that has offered a class
of
asset-backed securities involving the same asset class as this
offering.

2. While we note the bracketed disclosure you have provided on
page
S-58 in the context of risk factors, please add a separately
captioned section to disclose the affiliations and certain
relationships and related transactions of the transaction parties
as
provided in Item 1119 of Regulation AB.

3. As a follow-up to the comment above, while we note the
bracketed
disclosure you have provided on page S-55, please include a
separately captioned section to disclose any legal proceedings
pending against the sponsor, seller, servicer, depositor,
trustees,
issuing entity or other transaction parties that would be material
to
investors, if applicable.  Refer to Item 1117 of Regulation AB.

4. We note that your base prospectus indicates that the trusts may
include mortgage-backed securities.  However, the prospectus
supplement you have provided does not contemplate an offering of
securities backed by a pool of other securities.  Rather, it
appears
to contemplate the securitization of mortgages.  Please refer to
Section III.A.3(b) of SEC Release No. 33-8518 and tell us why you
have not provided us with a form of prospectus supplement that
outlines the format of deal-specific information regarding any
offerings of securities backed by pools of the securities to which
you refer in the base prospectus.  In this regard, we note that
appropriate information regarding the transaction parties, deal
structure and asset pool does not appear to have been provided.

Prospectus Supplement

Cover

5. We note your reference on the cover page to the use of
subordination as a form of credit enhancement.  However, there
does
not appear to be a corresponding discussion of the terms of such
subordination in the prospectus supplement.  Please revise
accordingly or advise.

6. When referring to transaction parties, please use the
terminology
set out in Regulation AB.  Please refer to Item 1101(f) of
Regulation
AB for the definition of issuing entity.  In this regard, please
revise your cover page, including the second to last sentence of
the
first paragraph, to refer to the issuing entity.  Refer to Item
1102(d) of Regulation AB.

7. Please highlight the cross- reference to the risk factors
section
by prominent type or in another manner.  Please refer to Item
501(b)
of Regulation S-K and Item 1102 of Regulation AB.

Dealer Prospectus Delivery Obligation, page S-4

8. Please move the dealer prospectus delivery obligation
disclosure
to the outside back cover of the prospectus.  See Item 502(b) of
Regulation S-K.

Summary of Prospectus Supplement, page S-6

9. The summary section should be just that, a summary.  Please
revise
this section to provide brief and concise information in the
summary
and to include cross-references, as appropriate, to the detailed
discussion in the document.  Please refer to Item 503(a) of
Regulation S-K and Item 1103(a) of Regulation AB.

10. We encourage you to provide a graphic illustration(s) of the
relationships among the parties to the transaction and the
structure
of the securities offered, such as the flow of funds and payment
priorities and allocations, including any subordination features,
as
this would assist an investor`s understanding of the transaction.
Refer to Item 1103(a) of Regulation AB.

Description of the Sponsor[s] [and Originator/Other Mortgage Loan
Sellers], page S-60

11. We note that, if deemed material, "certain static pool
information" will be made available by the depositor on its
website.
Please revise this bracketed language to confirm that you will
provide all information required by Item 1105 of Regulation AB.

Column`s Underwriting Standards, page S-61

12. Please expand this disclosure to provide all of the
information
required by Item 1111(a) of Regulation AB.  In this regard, while
we
note that Column`s underwriting standards are general and that
there
is no assurance that every loan will comply in all respects with
the
guidelines, the extent to which the underwriting standards and
criteria may be overridden is unclear.  Additionally, you should
expand your disclosure here or elsewhere in the prospectus
supplement
to clearly address the method and criteria by which the pool
assets
were selected for the transaction.

The Pooling and Servicing Agreement, page S-107

13. While we note the disclosure you have provided in this
section,
please revise to provide all of the information called for by Item
1108 of Regulation AB or advise.  For example, it does not appear
that you have provided all of the information called for by Item
1108(d) regarding back-up servicers.  Additionally, to the extent
material, you should provide statistical information regarding
servicer advances on the pool assets and the servicer`s overall
servicing portfolio for the last three years, as well as any
material
effect on the potential cash flows from assets that may result
from
the servicer`s ability to waive or modify terms or payments on the
assets.  Finally, provide disclosure responsive to Item 1108(c)(7)
regarding the custodial duties related to the assets.

14. We note your disclosure on page S-108 indicating that neither
you
nor the underwriters makes any representation or warranty as to
the
accuracy or completeness of certain servicing information.  We
also
note similar disclosure on pages S-101 and S-109.  A disclaimer of
liability for material information provided by the issuer or
underwriters or any of their affiliates is not appropriate.
Please
remove the disclaimer here and remove any other similar
disclaimers
in the prospectus.
15. We note the table fees and expenses that you have provided on
page S-107.  However, it appears that you should expand this table
to
provide all of the information required by Item 1113(c) of
Regulation
AB.  In this regard, we note that the table refers only to per
annum
fees, while your disclosure in other sections of the document
refer
to additional servicing compensation in the form of borrower-paid
fees.   Please revise accordingly.

Rating, page S-142

16. Describe any arrangements to have the ratings monitored while
the
securities are outstanding.  Refer to Item 1120 of Regulation AB.

Base Prospectus

Summary of Prospectus, page 4

17. While we note that foreign mortgage loans will not represent
more
than 10% of a related mortgage asset pool, please confirm that, if
applicable, you will describe any pertinent factors related to the
foreign jurisdiction that could materially affect payments on, the
performance of, or other matters relating to, the assets in the
pool
and the asset-backed securities.

Use of Proceeds, page 33

18. We note your statement that the net proceeds to be received
from
the sale of the offered certificates will be applied towards the
purchase of the related pool assets "[u]nless otherwise specified
in
the related prospectus supplement" and note that you have included
similar statements throughout the base prospectus.  Please note
that
a takedown off of a shelf that involves assets, structural
features,
credit enhancement or other features that were not described in
the
base prospectus will usually require either a new registration
statement, if to include additional assets, or a post-effective
amendment.  Also, please note that Securities Act Rule 409
requires
that the registration statement be complete at the time of
effectiveness except for information that is not known or
reasonably
available.  Please revise the base prospectus to describe the
assets,
credit enhancements or other structural features reasonably
contemplated to be included in an actual takedown.

Description of the Certificates

Payments on the Certificates, page 63

19. We note from page 65 that you will specify in the related
prospectus supplement the pass-through rate for each class of
interest-bearing certificates offered or, in the case of floating,
adjustable or variable pass-through rates, the method for
determining
such rate.  Please expand your disclosure in the base prospectus
to
identify the indices on which the floating or adjustable mortgage
rates may be based.  Additionally, please note that the only
indices
permitted under the definition of an asset-backed security are
indices similar to those involved in an interest rate swap or a
currency swap.  Refer to Section III.A.2. of SEC Release 33-8518.

Description of the Governing Documents

Evidence as to Compliance, page 81

20. While we note the disclosure you have provided in this section
regarding the delivery of reports prepared in accordance with Item
1122(d) of Regulation AB, the corresponding disclosure on page S-
132
does not appear to comply with Item 1122 of Regulation AB.  Please
revise accordingly or advise.
Description of Credit Support, page 82

Credit Derivatives, page 83

21. We note your disclosure on page 83 indicating that you may use
credit derivatives, including credit default swaps.  As this
disclosure seems to indicate that your credit support will not be
limited to interest rate or currency swaps, please delete your
disclosure relating to credit derivatives in this section and
throughout this document or advise us how the anticipated swaps
would
meet the definition of an asset backed security.  Please refer to
Section III.A.2.a of SEC Release No. 33-8518 and to Item 1115 of
Regulation AB for a description of permissible derivative
products.

Exhibits

22. We note your disclosure on page S-59 regarding agreements that
will be filed on Form 8-K after the closing date.  However, you
should file the finalized agreements at the time of each takedown.
Refer to 1100(f) of Regulation AB and revise or advise as
necessary.

Closing

      As appropriate, please amend your registration statement in
response to these comments.  You may wish to provide us with
marked
copies of the amendment to expedite our review.  Please furnish a
cover letter with your amendment that keys your responses to our
comments and provides any requested supplemental information.
Detailed cover letters greatly facilitate our review.  Please
understand that we may have additional comments after reviewing
your
amendment and responses to our comments.

      We urge all persons who are responsible for the accuracy and
adequacy of the disclosure in the filings reviewed by the staff to
be
certain that they have provided all information investors require
for
an informed decision.  Since the company and its management are in
possession of all facts relating to a company`s disclosure, they
are
responsible for the accuracy and adequacy of the disclosures they
have made.

	Notwithstanding our comments, in the event the company
requests
acceleration of the effective date of the pending registration
statement, it should furnish a letter, at the time of such
request,
acknowledging that:
?	should the Commission or the staff, acting pursuant to
delegated
authority, declare the filing effective, it does not foreclose the
Commission from taking any action with respect to the filing;

?	the action of the Commission or the staff, acting pursuant to
delegated authority, in declaring the filing effective, does not
relieve the company from its full responsibility for the adequacy
and
accuracy of the disclosure in the filing; and

?	the company may not assert staff comments and the declaration
of
effectiveness as a defense in any proceeding initiated by the
Commission or any person under the federal securities laws of the
United States.

      In addition, please be advised that the Division of
Enforcement
has access to all information you provide to the staff of the
Division of Corporation Finance in connection with our review of
your
filing or in response to our comments on your filing.

      We will consider a written request for acceleration of the
effective date of the registration statement as a confirmation of
the
fact that those requesting acceleration are aware of their
respective
responsibilities under the Securities Act of 1933 and the
Securities
Exchange Act of 1934 as they relate to the proposed public
offering
of the securities specified in the above registration statement.
We
will act on the request and, pursuant to delegated authority,
grant
acceleration of the effective date.

      We direct your attention to Rules 460 and 461 regarding
requesting acceleration of a registration statement.  Please allow
adequate time after the filing of any amendment for further review
before submitting a request for acceleration.  Please provide this
request at least two business days in advance of the requested
effective date.

      Direct any questions to Hanna Teshome at (202) 551-3315, or
in
her absence, to me at (202) 551-3454.

								Sincerely,

						                        Sara D.
Kalin
												Branch
Chief-Legal

cc:	via facsimile
	Pat T. Quinn, Esq.
	Cadwalader, Wickersham & Taft
	(212) 504-6666

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Credit Suisse First Boston Mortgage Securities Corp. (333-129918)
December 20, 2005
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