Outcome research is a relatively new field of investigation sparked by a number of changes in the health care system. One such movement – the promotion of evidence-based practice – has increased the demand for outcomes data. The recent explosion in the development of practice guidelines and clinical care maps has relied on outcome studies so as to ensure that these clinical guidelines are based on scientific knowledge. Furthermore, the expanding application of outcome measures in the clinical field has enabled service providers to audit ‘outcome’ information for particular populations, thereby altering and improving resources and programs, and prioritizing needs. In the field of research, the National Center for Medical Rehabilitation Research, USA has placed a high priority on this area of investigation.