OBJECTIVE: To investigate whether allied health therapy provided by caregivers improves patient outcomes. DATA SOURCES: Electronic databases MEDLINE, CINAHL, Embase, Allied Health Evidence, and Cochrane Central Register of Controlled Trials were searched from the earliest available date until July 2011. STUDY SELECTION: The search strategy included synonyms for allied health disciplines, caregivers, and randomized controlled trials. Of 1761 potentially relevant articles evaluated by 2 reviewers independently, 29 trials met inclusion criteria. DATA EXTRACTION: After data were extracted, 2 reviewers independently assessed the quality of trials using the Physiotherapy Evidence Database Scale. The Grading of Recommendations Assessment, Development and Evaluation approach was used to assess quality of evidence across studies. DATA SYNTHESIS: The 29 trials included 1196 participants and investigated speech and language therapy (n=19), physical therapy (n=2), social work (n=1), psychology (n=1), and combinations of 2 or more disciplines (n=6). Meta-analysis provided high-quality evidence that when compared with no intervention, caregiver-administered speech and language therapy improved language outcomes in children. Meta-analysis provided moderate-quality evidence that therapy provided by speech and language therapists was not superior to caregiver-administered therapy for children with speech impairments. The smaller number of physical therapy, psychology, and social work trials could not be combined in meta-analyses but provided examples of caregiver-administered therapy being more effective than no intervention and as effective as clinician-administered therapy. CONCLUSIONS: There is moderate-quality evidence that caregivers can be trained to provide effective speech and language therapy interventions. This approach needs more evaluation, but may be applicable in the disciplines of physical therapy, occupational therapy, social work, psychology, dietetics, and podiatry.