Job performance measures (JPM's) can be used to assess the quality of a police agency's formal and on-the-job training programs, as well as an individual officer's ability to perform the tasks of a particular law enforcement job. JPM's can also be used as part of a selection of screening processes for personnel management considerations such as promotion to a higher grade. What constitutes a job, a duty, a task, and an element are explained, and the report emphasizes that a JPM for a particular law enforcement task will have good predictive validity if someone who scores high on or passes the JPM can also perform the task on the street. The predictive validity and physical fidelity of various JPM tests are explained, and the types of simulation tests that can be performed are noted. To develop and validate JPM's, agencies should determine testing constraints, JPM conditions and cues, and the type of task JPM will measure, as well as JPM standards and other factors. Item specification sheets should be prepared to ensure that JPM's are consistent with the tasks and consistent with each other. Steps required to establish adequate test reliability and validity are outlined. Eight references, a suggested reading list, and a few tables are provided. Appendixes present four sample Florida police-related test items.