Performance appraisals are widely used as an HR instrument. This study among 332 police officers examines the effects of performance appraisals from a behavioral ethics perspective. A mediation model relating justice perceptions of police officers’ last performance appraisal to their work affect, perceived supervisor and organizational support and, in turn, their ethical (pro-organizational proactive) and unethical (counterproductive) work behavior was tested empirically. The relationship between justice perceptions and both, ethical and unethical behavior was mediated by perceived support and work affect. Hence, a singular yearly performance appraisal was linked to both ethical and unethical behaviors at work. The finding that ethical and unethical aspects of employee behavior share several of the same organizational antecedents, namely organizational justice perceptions, has strong practical implications which are discussed as well.