Theories examined concern the origin and functional significance of the incest taboo, the incest avoidance tendency, and explanations for adult-child incest. The review of descriptive adult-child incest research summarizes findings and critiques research biases, sampling and measurement problems, flawed definitions, and other research limitations. The research is synthesized into a model of adult-child incest, drawing upon ecological theories, conflict theory, exchange theory, and the literature on family power. The model is applied to prediction, prevention, and intervention. The study identifies incest risk factors from original research on adult-child incest cases reported statewide in Mississippi and Virginia in 1979. The review of the practice literature focuses on historical factors influencing rejection of treatment approaches that isolated the victim, competing perspectives impacting treatment and other practice decisions, and major incest treatment modalities. A therapeutic checklist, approximately 270 references, and author and subject indexes.