The purpose of the present chapter is to provide a broad and comprehensive description of the broad personality trait of Neuroticism (N). In addition to representing one of the most salient higher-order personality traits across different trait models, N shows great public health significance because of its robust predictive validity for many consequential outcomes (Barlow, Sauer-Zavala, Carl, Bullis, & Ellard, 2014; Lahey, 2009). In the present chapter, we begin by describing the broader N domain, including evidence for genetic and environmental influences on N. We then briefly discuss developmental considerations of N, including evidence for stability and change across the lifespan. We then turn to the relevance of trait N for predicting consequential outcomes in several relevant domains of functioning: psychopathology, physical health, and quality of life. We then summarize and end with suggestions for future directions in research and application.