The young field of research on dark personality traits (i.e., socially aversive traits such as psychopathy, narcissism, and Machiavellianism) is gaining momentum. This Special Section examines the nature, origins, development, and sequelae of dark traits, underscoring their largely unappreciated relevance to abnormal psychology. The articles in this section adopt diverse perspectives (e.g., clinical, developmental, organizational, social personality), use diverse methods (e.g., longitudinal, experience sampling), and sample diverse populations (e.g., offenders, psychiatric outpatients, schoolchildren). As an introduction to the Special Section, this article identifies key conceptual and methodological challenges to the field of dark personality research. Its aim is to spur novel approaches to how dark personality traits are implicated in psychopathology and abnormal behavior more broadly.