It is well established in the psychology literature that personality predicts performance to some degree. However, personality neither solely nor directly predicts outcomes. Rather, performance and outcomes unfold through context-specific mediating constructs. This study identified two constructs that mediate the relationship between proactivity and perceived control of time in e-mail use and tested the model with data from 251 knowledge workers. The results show that proactivity predicts the perceived control of time in e-mail use through both e-mail-specific time management behavior and e-mail self-efficacy. Further, greater e-mail self-efficacy leads to improved e-mail-specific time management behavior.