The ontogeny of self-injurious behaviour exhibited by young children with developmental delays or disabilities is due to a complex interaction between neurobiological and environmental variables. In this manuscript, the literature on emerging self-injury in the developmental disability population is reviewed with a focus on an operant conceptual model of how topographies of self-injurious behaviour can change structurally and become sensitive to various environmental consequences. Results of previous studies are reviewed in terms of extending our research focus from a reactive model of assessment and treatment of well-established cases of self-injury to an early intervention and prevention model.