Rehabilitation researchers who investigate complex interventions are challenged to describe the "active ingredients" of their interventions: the reason(s) why a treatment is expected to be effective. Interactive Computer Play (ICP) is an emerging complex intervention in rehabilitation practice and research. The purpose of this scoping review is to identify the active ingredients of ICP interventions that are designed to improve motor outcomes in children with neuromotor impairments. Eleven potential active ingredients were identified with the following foci: ICP system or game properties; intervention effects on the user; and therapist roles. However, few studies explicitly evaluate the impact of particular ingredients on outcomes. Identification of active ingredients in ICP interventions can inform trial design and clinical decision-making. Research and clinical practice will benefit from studies that utilize a framework such as motor learning theory to guide hypotheses and measurement of the active ingredients of complex interventions. (Contains 3 tables.)