A seminar on practical MARC cataloging was held at Southampton University library in April 1972. MARC is an acronym for Machine Readable Cataloging, a system devised by the Library of Congress and developed with them by the British National Bibliography. MARC enables the catalog data for any given work to be read and manipulated by the computer, which means that each record is broken down into its component parts, and each is given a symbol (a tag) which the machine is programmed to recognize when action is required on it. In MARC, the breakdown of each record and the tagging structure is as detailed as is practical. This is to give the computer as much flexibility as possible in handling the data. This text was prepared for the use of the participants in the working seminar, and is being made available with the intent that it will aid catalogers and library school students in gaining a brief introduction to the MARC system. (Author/SJ)