Although the experience of negative emotions is generally associated with negative behaviors and outcomes, researchers have largely overlooked the possibility that negative emotions can lead to proactive behavior. For instance, emotions such as anger and fear can spark proactive behavior by signaling a need to change the status quo. Whereas theory and research on the topic have produced conflicting arguments and inconsistent results, I integrate a discrete emotions perspective with theories of proactivity to determine the conditions under which anger and fear prompt proactive behavior. Doing so, I provide a conceptual framework that enables understanding of specific factors that determine when anger is directed away from fight that harms others and towards fight that benefits others, and when fear is directed away from flight and towards increased proactive effort (fight). This article contributes to theory with a contingent model that specifies when and why anger and fear spark proactive behavior and generate functional outcomes. It also offers practical advice for organizations to effectively manage emotional experiences and thereby increase proactive behavior resulting from experienced anger or fear.