This report constitutes Phase I of a two-part study; a Phase II report will discuss subject cataloging. Phase I is concerned with the materials of a library as individual records (or documents) and as representations of certain works by certain authors--that is, with descriptive, or bibliographic, cataloging. Discussed in the report are (1) the history, role, function, and objectives of the author-and-title catalog; (2) problems and principles of descriptive cataloging, including the use and function of "main entry", the principle of authorship, and the process and problems of cataloging print and nonprint materials; (3) organization of the catalog; and (4) potentialities of automation. The considerations inherent in bibliographic cataloging, such as the distinction between the"book" and the "work," are said to be so elemental that they are essential not only to the effective control of library's materials but also to that of the information contained in the materials. Because of the special concern with information, the author includes a discussion of the "Bibliographic Dimensions of Information Control," prepared in collaboration with Robert M. Hayes, which also appears in "American Documentation," Vol.20, July 1969, p. 247-252. (JW)