RecruitingBehavioural interventionMeasurement-Based Care (MBC) Implementation, Effectiveness, and Mechanisms of ChangeAlthough measurement-based care (MBC) is an evidence-based practice with known benefits, it is not always systematically implemented with fidelity. Questions remain regarding MBC's unique added value compared to usual care. Thus, the goal of this clinical trial is to investigate the implementation outcome, effectiveness, and mechanisms of change of measurement-based care in adult behavioral health. This study implemented MBC in adult ambulatory behavioral health and will test outcomes using a pragmatic randomized control trial within the RE-AIM (Reach, Efficacy, Adoption, Implementation, and Maintenance) framework. Researchers will compare three groups: 1) the Measurement-based care group, 2) the treatment-as-usual group, and 3) the waitlist control group. Participants will participate in weekly individual psychotherapy sessions for 12 sessions in total.