The purpose of this review is to discuss the importance of treatment efficacy research in language comprehension in MR/DD populations. Although receptive language deficit is an integral part of most MR/DD typologies, there have been relatively few studies evaluating the effectiveness or efficacy of treatment for this condition. Recently, there has been increased attention placed on auditory processing in children with disabilities, an aspect of cognition related to receptive language, but there have also been few studies investigating the effectiveness or efficacy of training designed to improve auditory processing. In addition to arguing that additional studies in this area are needed, the review includes several theoretical frameworks for addressing the treatment of receptive language deficits in MR/DD. (Contains 1 figure.)