This document discusses personality in the context of organizational behavior. It begins with definitions of personality and methods of measuring personality, including self-report surveys and observer ratings. It then covers determinants of personality like heredity. Two models of personality are explained in depth: the Myers-Briggs Type Indicator, which sorts people into 16 personality types; and the Big Five model, which identifies the traits of extraversion, agreeableness, conscientiousness, openness to experience, and emotional stability. Finally, several personality traits are defined, such as core self-evaluation, Machiavellianism, narcissism, self-monitoring, risk-taking, and proactive personality.