SUMMARYPerceptions of self-injurious behaviour as refractory to treatment, and of treatment outcomes as unpredictable, in children and adults with intellectual disabilities and/or autism may lead to treatment inertia or nihilism, restrictive practices and overuse of psychotropic medication in its management. Recent research suggests, however, that from infancy to young adulthood prospects for a positive outcome are fair, and markers predictive of treatment outcome have begun to be identified. In this clinical reflection we briefly describe this work, consider how it may contribute to case stratification, and outline current thinking on further functional differentiation of cases of SIB, promoting non-restrictive practices.