The chronic relapsing nature of heroin addiction can be explained from a family systems viewpoint. The addiction cycle is part of a family pattern involving a complex homeostatic system of interlocking feedback mechanisms. These serve to maintain the addiction and consequently the overall family stability. Drug-taking usually starts at adolescence. It is related to an intense fear of separation experienced by the family in response to the addict's attempts at individuation. The family becomes stuck at a particular developmental stage. Heroin provides a solution at several levels to the dilemma of whether or not to allow him independence. Paradoxically, it permits him to simultaneously be both close and distant, “in” and “out,” competent and incompetent, relative to his family of origin. This is pseudoindividuation. An understanding of these concepts, and their integration into a homeostatic model, can provide the basis for effective treatment.