Data were gathered through interviews and from official records over 12-month periods during 1983-85 in Cleveland, Oh., Minneapolis, Minn., Columbia, S.C., Madison and Milwaukee, Wisc., and the State of Wyoming. The analysis considered more than 8,000 probation cases, of which more than 2,000 contained a documented violation. Findings showed wide variations in the way that formal policies influenced probation officers' behaviors. Differences also existed in informal traditions. As a result, probation officers varied in their amount of discretion. Organizational tolerance for misbehavior and lack of supervisory review of decisions were the main factors affecting discretion. The types of offender misbehavior varied from one jurisdiction to another, and the nature of the violation was the main factor influencing the response by the probation officer. Data tables and appendixed study questionnaires.