ABSTRACT This research comprises 6 studies designed to examine approach and avoidance temperament as basic dimensions of personality. In Study 1, we developed direct measures of approach and avoidance temperament. In Study 2, we demonstrated that the approach and avoidance temperament variables are not epiphenomena of response biases. In Study 3, we documented the test-retest stability of the temperament variables. In Study 4, we documented that approach and avoidance temperament are separate from other like-valenced variables and may be construed as the core of these variables. In Study 5, we documented that approach and avoidance temperament are separate from chronic promotion and prevention foci. In Study 6, we distinguished the temperament variables from achievement goal variables and documented the temperament variables as antecedents of achievement goals and achievement goals as proximal predictors of performance. Approach and avoidance temperament are discussed as an ideal foundation for a strong, enduring structure of personality.