To summarize the efficacy of postacute rehabilitation and to outline future research strategies for increasing knowledge of its effectiveness. English-language systematic reviews that examined multidisciplinary therapy-based rehabilitation services for adults, published in the last 25 years and available through Cochrane, Medline, or CINAHL databases. We excluded multidisciplinary biopsychosocial rehabilitation programs and mental health services. Using the search term rehabilitation, 167 records were identified in the Cochrane database, 1163 meta-analyses and reviews were identified in Medline, and 226 in CINAHL. The Medline and CINAHL search was further refined with 3 additional search terms: therapy, multidisciplinary, and interdisciplinary. In summary, we used 12 reviews to summarize the efficacy of multidisciplinary, therapy-based postacute rehabilitation; the 12 covered only 5 populations. Two reviewers extracted information about study populations, sample sizes, study designs, the settings and timing of rehabilitation, interventions, and findings. Based on systematic reviews, the evidence for efficacy of postacute rehabilitation services across the continuum was strongest for stroke. There was also strong evidence supporting multidisciplinary inpatient rehabilitation for patients with rheumatoid arthritis, moderate to severe acquired brain injury, including traumatic etiologies, and for older adults. Heterogeneity limited our ability to conclude a benefit or a lack of a benefit for rehabilitation in other postacute settings for the other conditions in which systematic reviews had been completed. The efficacy of multidisciplinary rehabilitation services has not been systematically reviewed for many of the diagnostic conditions treated in rehabilitation. We did not complete a summary of findings from individual studies. Given the limitations and paucity of systematic reviews, information from carefully designed nonrandomized studies could be used to complement randomized controlled trials in the study of the effectiveness of postacute rehabilitation. Consequently, a stronger evidence base would become available with which to inform policy decisions, guide the use of services, and improve patient access and outcomes.