With increasing demand for psychotherapy services, clinicians are carrying increasingly large caseloads (Bailey et al., 2020). As the number of new intakes exceeds the number of clinical hours available each week in some settings, psychotherapy is delivered on an attenuated schedule for returning clients (rather than the traditional weekly frequency); there is, however, little support for the efficacy of this practice. The present study explored the effect of session frequency on psychotherapy outcomes using a quasi-randomized controlled design. In a working university counseling center, we assigned therapists to either a treatment-as-usual (TAU) group (attenuated session frequency) or an experimental group (weekly session frequency). Clients were randomly assigned to a therapist in either condition. Using hierarchical linear modeling and survival analyses, we examined psychotherapy outcomes (measured by session-by-session Outcome Questionnaire 45 scores) for 1,322 clients (3,919 individual sessions). We found no differences between groups when examining the full sample, but also found limited fidelity in the experimental group. When identifying individuals who were seen weekly in at least the first three sessions after intake (sensitivity analysis), we found the following: (a) weekly therapy resulted in faster trajectories of change over time, (b) weekly therapy resulted in a greater likelihood of achieving recovery, and (c) weekly therapy resulted in a greater likelihood of achieving recovery sooner. We discuss the importance of including session frequency when considering the dose of therapy, as well as the implication that prioritizing weekly therapy may increase therapy efficacy and efficiency in routine practice. (PsycInfo Database Record (c) 2022 APA, all rights reserved).