Participants were four randomly selected police officers at one station in Melbourne, Victoria, as well as citizens with whom they interacted over a period of a few weeks. Police officers were observed, and 80 customers were interviewed as they departed from the police station. The behavior-modification techniques studied included task clarification, the provision of reinforcement, and the use of corrective feedback. Results indicated that the behaviors that determine citizens' perceptions of courtesy are amenable to change through behavior modification. Task clarification via a workshop produced increases in overall courtesy for all participants, but for some people these changes began to deteriorate shortly after the workshop sessions. In contrast, the performance improvements following reinforcement and corrective feedback were smaller but more stable over time. Findings also indicated that most performance improvements were maintained over time, but the return of one participant's performance to baseline levels indicated the difficulty of maintaining performance change and the need for consistent monitoring and feedback. Finally, results also revealed that verbal responses and other behaviors under the individual's voluntary control were more amenable to improvement that were prompt attention and other behaviors influenced by external variables such as the amount of activity in the police station. Tables, figures, appended instrument and additional tables, and 24 references