While both scholars and practitioners have recognized the beneficial impacts of proactivity for employees and organizations, there is limited understanding regarding the social consequence of employees’ distinct forms of proactive behavior. Drawing on the socio-functional theory of emotion, we developed a theoretical model to explore coworkers’ different reactions to focal employees’ distinct forms of proactive behavior. We conducted a time-lagged experience sampling method (ESM) study to test the theoretical model. Results from the ESM study supported the positive relationship between employees’ career-oriented proactive behavior and coworkers’ undermining behavior via contempt for coworkers in high collectivism orientation and the positive relationship between employees’ work unit-oriented proactive behavior and coworkers’ support behavior via admiration for coworkers in high collectivism orientation. Our research contributes to the literature on the social consequence of proactivity and offers important practical implications for employees to wisely engage in proactive behaviors.