Few psychologists today are aware of the seminal role played by learning theorist Edward C. Tolman in the early development of the field of behavior genetics. Tolman was the first to publish a study of selective breeding for maze-learning ability in rats. He continued to foster research in this field by supporting the work of his students, particularly Robert C. Tryon. Tryon carried out the first major long-term study of maze-bright and maze-dull rats. This article focuses on Tolman's early years at Berkeley and the events culminating in the inheritance project, as well as on the evolution of this research under Tryon's direction.