Being proactive involves self-initiated, future-focused, and change-orientated behaviors. Such proactivity has been recognized as a positive way of behaving that can lead to the increased performance and effectiveness of individuals and organizations, especially when employees operate in contexts of unpredictable and changing demands. Because of its well-documented benefits, the antecedents and mechanisms of proactive behavior have been widely examined in an effort to identify how to promote such behavior in organizations. In this article, the authors first review various ways of conceptualizing proactivity, which includes an individual differences perspective, a behavior perspective, and a process perspective. A behavior perspective is mainly adopted in this article as this perspective is dominant in literature. Next, three mechanisms representing “can do”, “reason to” and “energized to” processes that can trigger proactive behavior are introduced. A review on antecedents of proactive behavior, including dispositional factors, situational factors and their interactions, is followed. The authors also summarize consequences that proactive behavior can bring, including job attitudes and performance. In addition to providing reviews, as the second part, the authors introduce their recent research that considers expanded dispositional predictors of proactive behavior (i.e., need for cognition, attachment style) as well as how these predictors interact with the situation. To conclude, the authors summarize what is well established in the literature, as well as what warrants further inquiry.