Although proactive behavior is important in organizations, it is not always appreciated by supervisors. To explain when supervisors reward proactivity with higher overall performance evaluations, we draw on attribution theory. We propose that employees’ values and affect send signals about their underlying intentions, which influence supervisors’ attributions about whether employees deserve credit for proactive behaviors. More specifically, we hypothesize that if employees express strong prosocial values or low negative affect, the proactive behaviors of voice, issue-selling, taking charge, and anticipatory helping will have stronger relationships with supervisors’ performance evaluations. We test these hypotheses with samples of 103 managers and their direct supervisors (Study 1) and 55 firefighters and their platoon supervisors (Study 2). The hypotheses were supported in both studies, suggesting that proactive behaviors are more likely to contribute to higher supervisor performance evaluations when employees express strong prosocial values or low negative affect.