We encounter people who possess socially undesirable personality traits at subclinical levels in our day to day lives, whether it is the boss who acts like a jerk, a cheating partner, or a friend who rubs everyone the wrong way. This volume explores the latest research on the assessment of dark personality traits, including the Dark Triad of narcissism, Machiavellianism, and psychopathy. The internationally renowned group of contributors provide a comprehensive, evidence-based overview of the personality traits currently being explored. Each chapter reviews two main topics. First, a particular measure used to study such traits is discussed. This section is geared to help the reader to understand how researchers in this area capture data on these traits and to best decide which instrument they want to use and when. Second, each chapter then details what the psychometric data on the test reveals about human nature, including topics such as sex differences, workplace behaviors, sexuality, and value systems. In this way, the contributors highlight how the convergence of research from various measures can provide a broad mosaic of information about people colloquially called psychopaths, narcissists, spiteful, Machiavellian, and sadists. This book is essential reading for anyone interested in test development and practitioners interested in the dark side of personality.