Objective: Training through traditional workshops is relatively ineffective for changing counseling practices. Teleconferencing supervision (TCS) was developed to provide remote, live supervision for training motivational interviewing (MI). Method: Ninety-seven drug treatment counselors completed a 2-day MI workshop and were randomized to live supervision via teleconferencing (TCS; n = 32), standard tape-based supervision (tape; n = 32), or workshop alone (workshop; n = 33). Supervision conditions received 5 weekly supervision sessions at their sites using actors as standard patients. Sessions with clients were rated for MI skill with the Motivational Interviewing Treatment Integrity (MITI) Coding System pre-workshop and 1, 8, and 20 weeks post-workshop. Mixed-effects linear models were used to test training condition on MI skill at 8 and 20 weeks. Results: TCS scored better than workshop on the MITI for spirit (mean difference = 0.76; p less than 0.0001; d = 1.01) and empathy (mean difference = 0.68; p less than 0.001; d = 0.74). TCS was superior to workshop in reducing MI non-adherence and was superior to workshop and tape in increasing reflection to question ratio. Tape was superior to TCS in increasing complex reflections. Percentage of counselors meeting proficiency differed significantly between training conditions for the most stringent threshold (spirit and empathy scores [greater than or equal to] 6). Conclusions: TCS shows promise for promoting new counseling behaviors following participation in workshop training. However, further work is needed to improve supervision methods to bring more clinicians to high levels of proficiency and facilitate dissemination of evidence-based practices. (Contains 3 tables and 2 figures.)