A new version of the Rational-Experiential Inventory (REI), which measures rational and experiential thinking styles and includes subscales of self-reported ability and engagement, was examined in two studies. In Study 1, the two main scales were independent, and they and their subscales exhibited discriminant validity and contributed to the prediction of a variety of measures beyond the contribution of the Big Five scales. A rational thinking style was most strongly and directly related to Ego Strength, Openness, Conscientiousness, and favorable basic beliefs about the self and the world, and it was most strongly inversely related to Neuroticism and Conservatism. An experiential thinking style was most strongly directly related to Extraversion, Agreeableness, Favorable Relationships Beliefs, and Emotional Expressivity, and it was most strongly inversely related to Categorical Thinking, Distrust of Others, and Intolerance. In Study 2, a rational thinking style was inversely related and an experiential thinking style was unrelated to nonoptimal responses in a game of chance. It was concluded that the new REI is a significant improvement over the previous version and measures unique aspects of personality.