One of the best ways to learn about personality is to start with one central concept and explore its relationships with many other concepts and processes that are applicable to the study of personality. Originally published in 1979, Extraversion and Introversion: An Interactional Perspective does precisely that, using the vehicle of extraversion–introversion to explore the psychology of personality. The result is exposure to such diverse topics as clinical disorders, reasons for smoking cigarettes, vocational interests, and popular personality traits at the time. The primary aim was to gain an understanding of the meaning and usefulness of extraversion–introversion in the light of the most current research, but the potential secondary gains were also numerous. Today it can be read in its historical context.