The MARC Pilot Project was an experiment conducted by the Library of Congress, in cooperation with 16 participating libraries, to determine the feasibility of putting cataloging data into machine-readable from for distribution of magnetic tapes. MARC (Machine Readable Cataloging) records were distributed for some 16,000 titles in the pilot phase from November 1966 through June 1967 and for additional titles in the following fiscal year while the project was in transition to an operational stage. By June 30, 1968, approximately 50,000 records had been distributed to the participants for use in the production of book catalogs, catalog cards, book selection notices, and other library tools. This final report by the project's director contains a detailed description of the MARC pilot system, including the tape format, character sets, bibliographic codes, and input procedures. An analysis of the cost of production during the pilot period, as well as brief summaries of the computer programs used, are provided. The new MARC system which evolved from work carried out in the project and which is used for the MARC Distribution Service is also described. An appendix includes the reports and analyses of the pilot project written by the participating libraries. (LC Information Bull.)