Personality psychology seeks both to understand how individuals differ from one another in behavior, motivation, emotion, and cognition and to explain the causes of those differences. The goal of personality neuroscience is to identify the underlying sources of personality traits in neurobiological systems. This chapter reviews neuroscience research on the traits of the Five Factor Model (the Big Five: Extraversion, Neuroticism, Openness/Intellect, Conscientiousness, and Agreeableness). The review emphasizes the importance of theoretically informed neuroscience by framing results in light of a theory of the psychological functions underlying each of the Big Five. The chapter additionally reviews the various neuroscientific methods available for personality research and highlights pitfalls and best practices in personality neuroscience.