Recent evidence suggests that psychotherapists may not increase in effectiveness over accrued experience in naturalistic settings, even settings that provide access to patients’ outcomes. The current study examined changes in psychotherapists’ effectiveness within an agency making a concerted effort to improve outcomes through the use of routine outcome monitoring coupled with ongoing consultation and the planful application of feedback including the use of deliberate practice. Data were available for 7 years of implementation from 5,128 patients seen by 153 psychotherapists. Results indicate that outcomes indeed improved across time within the agency, with increases of d = 0.035 (p = .003) per year. In contrast with previous reports, psychotherapists in the current sample showed improvements within their own caseloads across time (d = 0.034, p = .042). It did not appear that the observed agency-level improvement was due to the agency simply hiring higher-performing psychotherapists or losing lower-performing psychotherapists. Implications of these findings are discussed in relation to routine outcome monitoring, expertise in psychotherapy, and quality improvement within mental health care.