This study focuses on how patrol officers define their jobs differently from how their supervisors do in a single law enforcement agency. I identify the source, substance, and degree of these differences, and I explore the relationships between definitional differences and performance appraisal outcomes-perception of fairness and average appraisal scores. The job definitions are based on a factor analysis of the ratings of the importance of generally used performance appraisal categories. The ratings of the relative importance of the performance categories indicate that job definitions are generally idiosyncratic, although some consensus exists between the officers and supervisors on those dimensions of the job identified through the factor analysis procedure.