Twenty years of communication intervention research with individuals who have severe intellectual and developmental disabilities.

This literature review was conducted to evaluate the current state of evidence supporting communication interventions for individuals with severe intellectual and developmental disabilities. We reviewed 116 articles published between 1987 and 2007 in refereed journals meeting three criteria: (a) described a communication intervention, (b) involved one or more participants with severe intellectual and developmental disabilities, and (c) addressed one or more areas of communication performance. Many researchers failed to report treatment fidelity or to assess basic aspects of intervention effects, including generalization, maintenance, and social validity. The evidence reviewed indicates that 96% of the studies reported positive changes in some aspects of communication. These findings support the provision of communication intervention to persons with severe intellectual and developmental disabilities. Gaps in the research were reported as were recommendations for future research.