This article provides benchmark data on within-group effect sizes from published randomized controlled trials (RCTs) that evaluated the efficacy of research-supported treatments (RSTs) for adult traumatic stress. Agencies can compare these benchmarks to their treatment group effect size to inform their decisions as to whether the way they are adopting or adapting one of these RSTs is satisfactory or needs to be modified or replaced by a different intervention approach. These benchmarks also have potential utility for future implementation of research efforts about these RSTs that can assess what service provision conditions are associated with effect sizes that resemble the benchmarks provided in this study.