Chapter 3 offers an overview of historical and current research on personality traits and trait taxonomies. The authors begin by identifying three fundamental questions that guide trait psychologists: How should we conceptualize traits? How can we identify which traits are the most important traits from among the many ways in which individuals differ? How can we formulate a comprehensive taxonomy of traitsÑa system that includes within it all the major traits of personality?

Next, the authors present two basic formulations for defining traits: Traits as internal causal properties and traits as purely descriptive summaries of the attributes of persons. The authors present the act frequency formulation of traits as an example of the descriptive summary perspective. The authors then review three approaches to identifying the most important traits: Lexical, statistical, and theoretical approaches.

Finally, the authors review four major taxonomies of personality. 1) Eysenck's hierarchical model identifies three super-traits (Extraversion, Neuroticism, Psychoticism) and highlights biological underpinnings of basic traits; 2) Cattell's 16 Personality Factor system, which has received empirical support, but many argue it proposes too many "basic" traits; 3) The circumplex model of personality, which organizes interpersonal traits around a circle defined by two orthogonal dimensions of status and love; and finally 4) The five-factor model of personality (Surgency or Extraversion, Agreeableness, Conscientiousness, Emotional Stability, and Openness-Intellect), which dominates trait psychology today and was originally based on a combination of the lexical and statistical approaches. The five-factor model has achieved greater consensus among personality psychologists than any other taxonomy in the history of personality psychology. However, several questions remain for future work on the "Big Five," including identifying factors that may have been omitted from the taxonomy, and clarifying the content of the fifth factor.