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March 19, 2010

Ms. Patsy Mengiste
Securities and Exchange Commission
100 F Street, N.E.
Washington, D.C. 20549

ATTN: Document Control - EDGAR

RE: RiverSource Income Series, Inc. Post-Effective Amendment No. 106
RiverSource Income Builder Basic Income Fund File No. 2-10700/811-499
RiverSource Income Builder Enhanced Income Fund Accession No.: 0000950123-10-006771
RiverSource Income Builder Moderate Income Fund

RiverSource Market Advantage Series, Inc. Post-Effective Amendment No. 40
RiverSource Portfolio Builder Aggressive Fund File No. 33-30770/811-5897
RiverSource Portfolio Builder Conservative Fund Accession No.: 0000950123-10-006764
RiverSource Portfolio Builder Moderate Aggressive Fund
RiverSource Portfolio Builder Moderate Conservative Fund
RiverSource Portfolio Builder Moderate Fund
RiverSource Portfolio Builder Total Equity Fund
RiverSource S&P 500 Index Fund
RiverSource Small Company Index Fund

RiverSource Money Market Series, Inc. Post-Effective Amendment No. 68
RiverSource Cash Management Fund - Class Z shares File No. 2-54516/811-2591
Accession No.: 0000950123-10-006870

Dear Ms. Mengiste:

This letter responds to your comments received by telephone on March 11, 2010
with respect to the above-referenced Funds' Form N-1A post-effective amendments
filed pursuant to Rule 485(a) of the Securities Act of 1933, as amended, on
January 29, 2010 (the "Filings").

RiverSource Small Company Index Fund and RiverSource S&P 500 Index Fund

COMMENT 1: Does the Fund have a higher commitment than the stated 80% policy? If
not, explain why.

RESPONSE: While each of the Funds have an 80% policy, the investment manager
expects the correlation between the performance of the Funds and their
respective index to be at least 0.95. This expectation is currently reflected in
the principal investment strategies for RiverSource S&P 500 Index Fund. The
principal investment strategies for RiverSource Small Company Index Fund will be
revised to reflect this expectation.

COMMENT 2: Please include the Fund's correlation test in the Summary section of
the prospectus.

RESPONSE: The principal investment strategies in the Summary section for the
RiverSource Small Company Index Fund prospectus will be so revised. The existing
principal investment strategies in the Summary section of the RiverSource S&P
500 Index Fund prospectus include such disclosure.

COMMENT 3: Will the Fund notify shareholders of a change in the Index?

RESPONSE: Since the 80% policy of the Fund includes the specific index by name,
the Fund will provide shareholders 60 days' written notice of a change in the
index.

COMMENT 4: In the Principal Investment Strategies of the Fund section on page
10p of the RiverSource S&P 500 Index Fund prospectus, there appears to be some
duplicative text. If so, please remove.

RESPONSE: The disclosure that appeared as the first paragraph of text on page
10p has been deleted.

RiverSource Income Builder Funds and RiverSource Portfolio Builder Funds

COMMENT 1: On the Table of Contents page, (a) please consider revising the lead
in paragraph at the top of the page, and (b) move the paragraph at the bottom of
the page to either the cover page or following Items 2 - 8 of the Form.

RESPONSE: (a) The information under the heading "Summary of the Funds" is there
to represent the various subsections in the Summary. In a multiple fund
prospectus, we believe we are complying with Rule 481(c) to provide a reasonably
detailed table of contents. We will adjust the formatting to make it look more
like part of the table of contents.

(b) The paragraph at the bottom of the Table of Contents page will be deleted.

COMMENT 2: Please remove the second sentence under the Investment Objective
portion of the Summary of the Fund.

RESPONSE: The sentence will be deleted.

COMMENT 3: In the first paragraph under Fees and Expenses of the Fund,
everything after the first sentence needs to be deleted. The disclosure should
be the same as for other funds.

RESPONSE: The disclosure will be deleted.

COMMENT 4: Footnote (c) to the Annual Fund Operating Expenses table should not
include disclosure regarding the waivers or expenses reimbursed for the
underlying funds.

RESPONSE: The fee cap in place for the Fund excludes the fees and expenses of
the underlying funds' and, therefore, fees a Fund shareholder bears indirectly
from the underlying funds could increase a Fund shareholder's expenses above the
cap in place at the Fund level. Because we believe the footnote regarding the
contractual waiver/reimbursement for the acquired funds (underlying funds) is
material to Fund shareholders' understanding of the fees and expenses that he or
she can expect to bear as an investor in the Fund, we respectfully prefer to
include such information.

COMMENT 5: In the Principal Investment Strategies of the Fund, include further
detail regarding how the investment manager intends to meet the Fund's
investment objective. For example, include the types of equity funds that the
Fund anticipates investing in.

RESPONSE: The Principal Investment Strategies of the Fund will be revised by
adding the following:

RiverSource Income Builder funds:

INVESTMENT CATEGORY ALLOCATION. Within the equity and fixed income asset
classes, the quantitative model establishes allocations for the Fund,
seeking to achieve the Fund's objective by investing in defined investment
categories. Fixed income investment categories include underlying funds
that invest in: treasury inflation protected securities, mortgage- and
asset-backed securities, core plus (primarily domestic investment grade
bonds), high yield bonds, high yield loans, international bonds and
emerging markets bonds. The investment manager also may allocate assets to
money market (cash) or alternative investment strategy funds. Equity
investment categories include underlying funds that invest in: U.S. large
cap, mid cap and small cap equities (including growth, value and core/blend
styles), international equities (including emerging market securities) and
real estate securities. The target allocation range constraints are
intended to

promote diversification within the asset classes, and the quantitative
model takes into account factors such as style, sector, market
capitalization, geographic location, credit quality, interest rate risk,
and yield potential. Proposed allocation shifts are reviewed and approved
by the investment manager as part of its qualitative review.

For RiverSource Portfolio Builder Conservative Fund

For RiverSource Portfolio Builder Moderate Conservative Fund

The Fund invests primarily in underlying funds that invest in fixed income
securities such as treasury bonds and notes, treasury inflation protected
securities, mortgage securities, investment grade corporate bonds, high
yield bonds, high yield loans and international bonds, each with varying
interest rates, terms, duration, and credit exposure, and also invests a
moderate amount in underlying funds that invest in equity securities of
different investment styles (e.g., growth, value and core/blend), market
capitalizations (large, mid and small cap) and geographic location (both
domestic and international), as well as underlying funds with exposure to
real estate securities.

For RiverSource Portfolio Builder Moderate Fund

The Fund invests in a balance of underlying funds that invest in fixed
income securities such as treasury bonds and notes, treasury inflation
protected securities, mortgage securities, investment grade corporate
bonds, high yield bonds, high yield loans and international bonds, each
with varying interest rates, terms, duration, and credit exposure, and
underlying funds that invest in equity securities of different investment
styles (e.g., growth, value and core/blend), market capitalizations (large,
mid and small cap) and geographic location (both domestic and
international), as well as underlying funds with exposure to real estate
securities.

For RiverSource Portfolio Builder Moderate Aggressive Fund

The Fund invests primarily in underlying funds that invest in equity
securities of different investment styles (e.g., growth, value and
core/blend), market capitalizations (large, mid and small cap) and
geographic location (both domestic and international), as well as
underlying funds with exposure to real estate securities, and also invests
a moderate amount in underlying funds that invest in fixed income
securities such as treasury bonds and notes, treasury inflation protected
securities, mortgage securities, investment grade corporate bonds, high
yield bonds, high yield loans and international bonds, each with varying
interest rates, terms, duration and credit exposure.

For RiverSource Portfolio Builder Aggressive Fund

The Fund invests primarily in underlying funds that invest in equity
securities of different investment styles (e.g., growth, value and
core/blend), market capitalizations (large, mid and small cap) and
geographic location (both domestic and international), as well as
underlying funds with exposure to real estate securities, and also invests
a small amount in underlying funds that invest in fixed income securities
such as treasury bonds and notes, treasury inflation protected securities,
mortgage securities, investment grade corporate bonds, high yield bonds,
high yield loans and international bonds, each with varying interest rates,
terms, duration and credit exposure.

For RiverSource Portfolio Builder Total Equity Fund

COMMENT 6: Identify the categories of risks for the underlying funds in the
Summary section of the prospectus for each Fund.

RESPONSE: The language presented in the "Risks of Underlying Funds" section will
be revised to reflect differences in asset classes each fund-of-fund intends to
invest in as presented below. The bracketed language will vary depending on each
Fund's specifics:

RISKS OF UNDERLYING FUNDS. By investing in a combination of underlying
funds, the Fund has exposure to risks of many areas of the market. Since
[fund name] intends to invest a significant portion of its assets in
[equity and fixed income asset classes], the Fund may have higher exposure
to the following principal risks of the underlying funds: [Active
Management Risk, Counterparty Risk, Credit Risk, Derivatives Risk, Interest
Rate Risk, Issuer Risk, Market Risk, Prepayment and Extension Risk, Small
and Mid-Sized Company Risk.] Also, in addition to the Fund's operating
expenses, you will indirectly bear the operating expenses of the underlying
funds. Thus, the expenses you bear as an investor in the Fund will be
higher than if you invested directly in the underlying funds. Descriptions
of the more common principal risks to which the underlying funds (and thus,
the Fund) are subject to are identified under "More Information about the
Funds - Principal Risks of Investing in the Funds - Certain Principal Risks
of the Underlying Funds." A more complete list of principal risks
associated with direct investment in the underlying funds is set forth in
Appendix B. Additional risks of the underlying funds are set forth in the
SAI.

RiverSource Cash Management Fund - Class Z shares

COMMENT: With respect to Concentration Risk, please clarify what industry the
Fund may concentrate in and specify the risks associated with that particular
industry.

RESPONSE: The Concentration Risk disclosure will be revised to state:

INDUSTRY CONCENTRATION RISK. Investments that are concentrated in a
particular industry will make the Fund's portfolio value more susceptible
to the events or conditions impacting that particular industry. Because the
Fund may invest more than 25% of its total assets in money market
instruments issued by banks, the value of these investments may be
adversely affected by economic, political or regulatory developments in or
that impact the banking industry.

In connection with the Filings listed above, each Registrant hereby acknowledges
the following:

The disclosures in the filing are the responsibility of the Registrant and
the Registrant is fully responsible for the adequacy or accuracy of the
disclosures in the filing. The Registrant represents to the Commission that
comments made by the Commission, or the staff acting pursuant to delegated
authority, or changes to disclosure in response to staff comments in the
filing reviewed by the staff, do not foreclose the Commission from taking
any action with respect to the filing, and the Registrant represents that
it will not assert this action as a defense in any proceeding initiated by
the Commission or any person, under the federal securities laws of the
United States.

If you have any questions, please contact either me at (212) 850-1703 or Erin
Nygard at (612) 671-2543.

Sincerely,

/s/ Joseph L. D'Alessandro
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Joseph L. D'Alessandro
Vice President and Group Counsel
Ameriprise Financial, Inc.