The Ames Selective Dissemination of Information (SDI) System is an attempt to efficiently place rapidly increasing amounts of information into the hands of scientists and engineers who can exploit it. It is a computerized current awareness system designed to increase researchers' literature searching capabilities by bringing to their attention documents of potential interest from sources which they do not ordinarily search or from sources with which they may be unfamiliar. This operating manual is intended to provide those Ames SDI users who are participating through the Center for Industrial Research and Services (CIRAS) with a functional knowledge of the system, thereby enabling them to use it to maximum advantage. The emphasis in the manual is on what the system does and profile design rather than the inner workings of the computer programs involved. (Author/CC)