To examine whether the results of effectiveness studies match those obtained for efficacy studies on the same treatments, we conducted a focused review of the published treatment effectiveness literature. A literature search yielded 35 effectiveness studies for adult disorders (N = 21) and child and adolescent disorders (N = 14). A comparison of data from these studies with benchmarks from recent reviews of efficacy trials revealed treatment completion rates comparable with those found in the efficacy benchmarks. The improvement rates were comparable in effectiveness studies with those reported in randomized clinical trials of treatment efficacy. Despite methodological limitations in many effectiveness studies, these initial data provide encouraging support for the transportability to clinical settings of treatments with established efficacy.