FEBRUARY 3, 2000
SECURITIES AND EXCHANGE COMMISSION
JUDICIARY PLAZA
450 FIFTH STREET, N.W.
WASHINGTON, D.C.
RE: CALVERT SOCIAL INVESTMENT FUND
2-75106 AND 811-3334
IN LIEU OF FILING UNDER PARAGRAPH (B) OR (C) OF SECTION 497, THE
ABOVE REGISTRANT IS HEREBY FILING A CERTIFICATION THAT:
(1) THE FORM OF STATEMENT OF ADDITIONAL INFORMATION THAT WOULD HAVE
BEEN FILED UNDER PARAGRAPH (B) OR (C) OF SECTION 497 WOULD NOT HAVE DIFFERED
FROM THE ONE CONTAINED IN THE MOST RECENT REGISTRATION STATEMENT (EFFECTIVE
JANUARY 31, 2000) OR AMENDMENT; AND
(2) THE TEXT OF THE MOST RECENT REGISTRATION STATEMENT (EFFECTIVE
JANUARY 31, 2000) HAS BEEN FILED ELECTRONICALLY.
IF YOU HAVE QUESTIONS OR REQUIRE FURTHER INFORMATION, PLEASE CONTACT
ME AT 301-951-4881.
SINCERELY,
/S/SUSAN WALKER BENDER
ASSOCIATE GENERAL COUNSEL
