Committee reports beginning with the 104th Congress (1995-96) may be found on the Congress.gov Committees Page. Reports can be searched or browsed using the options on the right hand sidebar of this page.
Selected House and Senate reports from the 78th Congress (1943) to date are included in US Code Congressional and Administrative News (USCCAN), available in many law libraries, including the Law Library Reading Room.
Committee reports are printed as part of the United States Congressional Serial Set. The Serial Set is available at the Law Library of Congress, as well as some libraries in the Federal Depository Library Program.
The Serial Set is indexed by the Congressional Information Service (CIS) US Serial Set Index (1789-1969) and the CIS Annual Index (1970 to present). The CIS indexes and full text of the Serial Set reports and documents may be searched electronically on the Proquest Congressional database, available on Library computers.
Some research libraries that do not subscribe to the Serial Set and CIS Annual Index module of Proquest Congressional may have the microfiche sets that correspond to the CIS indexes.
Conference committee reports, in addition to being published as separate reports, are usually printed in the Congressional Record