The concept of passion is one we regularly use to describe our interests, and yet there is no broad theory that can explain the development and consequences of passion for activities across people's lives. In The Psychology of Passion, Robert J. Vallerand presents the first such theory, providing a complete presentation of the Dualistic Model of Passion and the empirical evidence that supports it. Vallerand conceives of two types of passion: harmonious passion, which remains under the person's control, and obsessive passion, which controls the person. While the first typically leads...