This book presents sensemaking strategies to support security planning and design. Threats to security are becoming complex and multifaceted and increasingly challenging traditional notions of security. The security landscape is characterized as 'messes' and 'wicked problems' that proliferate in this age of complexity. Designing security solutions in the face of interconnectedness, volatility and uncertainty, we run the risk of providing the right answer to the wrong problem thereby resulting in unintended consequences. Sensemaking is the activity that enables us to turn the ongoing complexity of the world into a "situation that is comprehended explicitly in words and that serves as a springboard into action" (Weick, Sutcliffe, Obstfeld, 2005). It is about creating an emerging picture of our world through data collection, analysis, action, and reflection. The importance of sensemaking to security is that it enables us to plan, design and act when the world as we knew it seems to have shifted. Leveraging the relevant theoretical grounding and thought leadership in sensemaking, key examples are provided, thereby illustrating how sensemaking strategies can support security planning and design. This is a critical analytical and leadership requirement in this age of volatility, uncertainty, complexity and ambiguity that characterizes the security landscape. This book is useful for academics, graduate students in global security, and government and security planning practitioners.