The author discusses the history and current use of undercover operations in law enforcement, Government and military services, and business and industry. He suggests appropriate staff recruitment procedures, with tips on personnel screening (psychological and memory retention tests along with polygraph examinations are essential). Notable industrial and corporate training programs are described and the need for formal training in handling physical evidence emphasized. The text explains how to establish a proper cover story, particularly if the agent has to establish credit or must infiltrate a criminal gang or industry. Agents should master the art of 'roping' -- or immersing themselves totally in the criminals' world in order to gain their confidence -and must be able to distinguish this activity from entrapment. The author advises agents on how to give testimony and to respond to cross-examinations. Report writing techniques and procedures for communicating with superiors while undercover are suggested. The report also covers how to respond when accused of being a 'stool pigeon,' how to conduct shopping investigations, and how to conduct surveillances. Tables, footnotes, an index, and about 25 references are supplied. Examples of actual undercover operations illustrate the author's main points.