This paper opens by describing research since 1975 (McCrae and Costa) on a set of related traits that identified as aspects of Openness to Experience. The historic roots of the concept of Openness to Experience are traced. Data are provided on the convergent and discriminant validity of the six Revised NEO-Personality Inventory facets of Fantasy, Aesthetics, Feelings, Actions, Ideas, and Values. Factor analyses are reported that demonstrate that these traits covary to define a broad dimension that can appropriately be called "Openness." It is shown that they are weakly and inconsistently related to psychometric measures of intelligence and to self-report measures of Intellectance that emphasize academic ability. These data are claimed to suggest that the fifth basic dimension of personality is better constructed as Openness than as Intellect. Finally, the book, "A Natural History of the Senses," by Diane Ackerman, is introduced and recommended for those who wish to gain a phenomenological perspective on Openness. (Contains 30 references.) (ABL)