Background: There is an over proliferation of evidence-based psychotherapies for anxiety and depression. These treatments share strategies, and yet, knowledge of which order of components is most efficacious and what mediators explain change within each strategy is limited. Greater understanding can help improve patient outcomes. Methods: Six patients with elevated levels of anxiety and/or depression were treated with a component of behavior therapy and a component of cognitive therapy using a series of multiple-baseline single-case experimental designs. Patients were randomized to receive behavior therapy first or cognitive therapy first, and they were administered self-report and behavioral measures daily, weekly, and at pre-, mid-, post- and follow-up assessments. Individual and aggregate effect size estimates were calculated for each outcome measure to assess order and incremental effects. Visual inspection was conducted to identify potential mediators. Results: Patients improved from therapy from pre- to post-treatment. Effect size estimates suggest that patients experience greater improvement in reducing negative outcomes from receiving the behavioral component first and greater improvement in increasing positive outcomes from receiving the cognitive component first. Incremental effects followed these trends with the cognitive component demonstrating a greater incremental effect over the behavioral component in reducing negative outcomes than the converse, and with the behavioral component demonstrating a greater incremental effect over the cognitive component in increasing positive outcomes than the converse. Implications: Results suggest that patients likely exhibit greatest improvement in reducing negative outcomes from receiving behavioral therapy followed by cognitive therapy and greatest improvement in increasing positive outcomes from receiving cognitive therapy followed by behavior therapy. Further implications of mediators are discussed.