Research on the contextual antecedents of employee silence remains underdeveloped. We propose supervisors' coercive and reward power as important antecedents of employee silence. Furthermore, guided by the person-environment interaction perspective, we suggest that two employee personality traits - conscientiousness and neuroticism - moderate the relationship between perceived supervisor power and employee silence. We conducted a two-wave survey of 177 full-time employees in China and found that employees were (a) more likely to remain silent when they perceived that their supervisor had high coercive power and (b) less likely to remain silent when they perceived that their supervisor had high reward power. These relationships were stronger for employees with a low level of conscientiousness or a high level of neuroticism. We discuss the theoretical and practical implications of our findings.