There has been roughly 15 years of research into approaches for aligning research in Human Computer Interaction with computer Security, more colloquially known as usable security.'' Although usability and security were once thought to be inherently antagonistic, today there is wide consensus that systems that are not usable will inevitably suffer security failures when they are deployed into the real world. Only by simultaneously addressing both usability and security concerns will we be able to build systems that are truly secure. This book presents the historical context of the work to date on usable security and privacy, creates a taxonomy for organizing that work, outlines current research objectives, presents lessons learned, and makes suggestions for future research.