Report of Independent Registered Public Accounting Firm
To the Board of Directors and Shareholders of Calvert
Responsible Index Series, Inc.:

In planning and performing our audits of the financial
statements of Calvert US Large-Cap Core Responsible Index
Fund, Calvert US Large-Cap Growth Responsible Index Fund,
Calvert US Large-Cap Value Responsible Index Fund, Calvert
International Responsible Index Fund, and Calvert US Mid-
Cap Core Responsible Index Fund, each a series of Calvert
Responsible Index Series, Inc. (hereafter referred to as the
Funds), as of and for the year ended September 30, 2019, in
accordance with the standards of the Public Company
Accounting Oversight Board (United States), we considered
the Funds' internal control over financial reporting, including
controls over safeguarding securities, as a basis for designing
our auditing procedures for the purpose of expressing our
opinion on the financial statements and to comply with the
requirements of Form N-CEN, but not for the purpose of
expressing an opinion on the effectiveness of the Funds'
internal control over financial reporting. Accordingly, we
express no such opinion.

Management of the Funds is responsible for establishing and
maintaining effective internal control over financial reporting.
In fulfilling this responsibility, estimates and judgments by
management are required to assess the expected benefits and
related costs of controls. The Funds' internal control over
financial reporting is a process designed to provide reasonable
assurance regarding the reliability of financial reporting and
the preparation of financial statements for external purposes in
accordance with generally accepted accounting principles. The
Funds' internal control over financial reporting includes those
policies and procedures that (1) pertain to the maintenance of
records that, in reasonable detail, accurately and fairly reflect
the transactions and dispositions of the assets of the Funds; (2)
provide reasonable assurance that transactions are recorded as
necessary to permit preparation of financial statements in
accordance with generally accepted accounting principles, and
that receipts and expenditures of the Funds are being made
only in accordance with authorizations of management and
Directors of the Funds; and (3) provide reasonable assurance
regarding prevention or timely detection of unauthorized
acquisition, use, or disposition of the Funds' assets that could
have a material effect on the financial statements.

Because of its inherent limitations, internal control over
financial reporting may not prevent or detect misstatements.
Also, projections of any evaluation of effectiveness to future
periods are subject to the risk that controls may become
inadequate because of changes in conditions, or that the
degree of compliance with the policies or procedures may
deteriorate.

A deficiency in internal control over financial reporting exists
when the design or operation of a control does not allow
management or employees, in the normal course of
performing their assigned functions, to prevent or detect
misstatements on a timely basis. A material weakness is a
deficiency, or a combination of deficiencies, in internal
control over financial reporting, such that there is a reasonable
possibility that a material misstatement of the Funds' annual
or interim financial statements will not be prevented or
detected on a timely basis.

Our consideration of the Funds' internal control over financial
reporting was for the limited purpose described in the first
paragraph and would not necessarily disclose all deficiencies
in internal control that might be material weaknesses under
standards established by the Public Company Accounting
Oversight Board (United States). However, we noted no
deficiencies in the Funds' internal control over financial
reporting and its operation, including controls over
safeguarding securities that we consider to be a material
weakness as defined above as of September 30, 2019.

This report is intended solely for the information and use of
management and the Board of Directors of the Funds and the
Securities and Exchange Commission and is not intended to be
and should not be used by anyone other than these specified
parties.

/s/ KPMG LLP

Philadelphia, Pennsylvania
November 20, 2019