TANLEY SCHACHTER WAS ONE of the very few social psychologists ever elected to the National Academy of Sciences (in 1983). His contributions ranged across the study of communication and social influence, group processes, sources of the affiliation motive, intellectual and temperamental correlates of birth order, nature of emotional experience, people's ability to correctly attribute the causes of their behavior to external versus internal factors, causes of obesity and eating behavior disorders, the addictive nature of nicotine, psychological reactions to events that affect stock market prices, and the proper interpretation of "filled" ("uh," "er") pauses in speech. Few, if any, social psychologists ever made contributions over a wider range of topics. Remarkably, the diverse content of the contributions was tied together by a small number of powerful theoretical concepts.