The present study investigates the impact of therapist experience treating clients on outcomes for future clients with similar demographic and clinical characteristics. Prior research has consistently failed to demonstrate that therapists with more experience (i.e. years of experience working with patients) are more effective than therapists with less experience. However, the literature is often criticized for failing to control for variables such as the amount and type of patients treated across therapist comparisons. The samples for the current study are taken from a larger national sample of 2366 outpatients receiving psychotherapy from across 92 therapists. The overall sample includes 83 matched pairs of patients across 83 of the 92 original therapists. Results indicate that therapists may be able to use prior experience with a patient to enhance future outcomes as long as latter patients are clinically and demographically similar and enter treatment shortly after the initial patient. Implications for how therapists are trained and use experience are discussed. Copyright © 2005 John Wiley & Sons, Ltd.