This book provides a detailed review of the key leadership theories and skills required during times of crises and radical uncertainty, how these can be developed, and how they can be applied in practice. Written over the course of the 2020 pandemic, the book highlights the immense lack of leadership competencies required for effective leadership in times of radical uncertainty and provides in-depth insights into the capacities and skills that should be part of all leadership development. The latest leadership theories, as well as existing key styles, including mindful leadership, the neuroscience of leadership, and transpersonal and adaptive leadership, are discussed and critiqued along with their potential contribution to developing effective leaders. Each chapter concludes with a convenient executive summary and questions that can be used for teaching purposes and class discussion. This is a comprehensive book about the interdisciplinary and multifaceted requirements of leadership and how to attain those capacities to develop effective leaders. It will be valuable for advanced undergraduate as well as postgraduate courses as a foundational resource on leadership theory and its application in practice.