We evaluated a 2-day training workshop on motivational interviewing (MI) for addiction and mental health clinicians (n = 22). Clinicians completed the helpful responses questionnaire (HRQ) and taped interactions with a standardized patient (SP). Independent, blinded coders rated the tapes using the motivational interviewing skills code (MISC). Post-training assessment showed significant increase on the HRQ and two of four MISC summary scores for SP interviews. At 2-month follow-up, means of the HRQ and two MISC summary scores remained higher than baseline, but declined from post-training. Some MI skills improved to a greater degree than others, and a subset of clinicians (> 40%) showed continued improvement at follow-up. Results were consistent across interviews with different SPs, supporting the use of this assessment method. Findings highlight the need for additional research on the use of standardized patients, alternative assessment techniques, and effective methods of technology transfer for MI skill acquisition and retention.