The structural analysis of incest is based in Larson's (1980) concept that incest reflects disturbances in four 'boundary' areas: the boundary between the family and its social environment, the boundary between adult and child generations in the family, interpersonal/role boundaries between family members, and intrapsychic boundaries within family members. A 'boundary' delineates the organizational wholeness of a given system. Incest reflects a family system that is relatively closed, undifferentiated, and rigid in both structure and function. The functional typology of incest families identifies four basic functions in interpersonal exchanges: the affectional process, the erotic process, the aggression process, and the rage-expression process. When placed on a continuum and integrated with other functional variables, this typology is useful in assessing and treating incestuous families. The particular meaning and function of the incestuous behavior in a given system must be addressed in planning treatment and evaluating its effectiveness. 28 references.