Several scholars have recently emphasized the important role of action in the practice of management. They have also noted the lack of managerial action-taking - the knowing-doing-gap - as a serious problem in companies. Although the critical role of managerial action-taking is widely acknowledged, theory on managerial action and its determinants remains underdeveloped. Weick's (1979) statement seems almost as valid now as it was twenty five years ago: "One of the ironies in organizational analysis is that managers are described as 'all business,' 'doers,' 'people of action,' yet no one seems to understand much about their acting."The central aim of this book is to contribute to a better understanding of managerial action. More specifically, the study focuses on two central research questions:What characterizes managerial action and non-action?The study shows that leaders' action represents a specific form of behavior that relies on the combination of two characteristics: Energy and focus. Purposeful action-taking implies that managers' behavior is energetic, i.e. is subjectively meaningful, is self-starting, and requires effort. Such behavior is clearly focused, i.e. oriented to the long term, directed towards a consciously chosen goal, and disciplined. Why do some managers act while others do not? Based on two qualitative studies and a multi-disciplinary literature review, a model of the emergence of leaders' action was developed and tested in a quantitative study. The empirical findings suggest that managers are more likely to take purposeful action when they have specific, challenging goals and believe in their ability to attain them (high, cognitive motivation) when they have positive, task-related emotions (high, emotional motivation) and the will to achieve a certain objective (high volition). Managers appear more likely to act in certain contexts, i.e. when they perceive choices, receive support from their superiors, and have good non-hierarchical relationships inside or outside the organization.