Harry Stack Sullivan, the founder of interpersonal psychoanalysis, was a gay man. His sexuality, far from being an incidental aspect of his life, was integral to his clinical and theoretical innovations. Sullivan was also a path-breaker in dealing with many aspects of gay civil rights that are still at issue today. Sullivan's writings about lust and sexuality have been difficult to understand and relatively ignored. When one decodes Sullivan's neologisms, one can appreciate how he was working toward a radical new formulation of sexuality's place in human living.