BACKGROUND: Shared decision making is a crucial component of evidence-based practice, but a lack of training in the "how to" of it is a major barrier to its uptake. OBJECTIVE: To evaluate the effectiveness of a brief intervention for facilitating shared decision making skills in clinicians and student clinicians. DESIGN: Multi-centre randomized controlled trial. PARTICIPANTS: One hundred and seven medical students, physiotherapy or occupational therapy students undertaking a compulsory course in evidence-based practice as part of their undergraduate or postgraduate degree from two Australian universities. INTERVENTION: The 1-h small-group intervention consisted of facilitated critique of five-step framework, strategies, and pre-recorded modelled role-play. Both groups were provided with a chapter about shared decision making skills. MAIN MEASURES: The primary outcome was skills in shared decision making and communicating evidence [Observing Patient Involvement (OPTION) scale, items from the Assessing Communication about Evidence and Patient Preferences (ACEPP) Tool], rated by a blinded assessor from videorecorded role-plays. Secondary outcomes: confidence in these skills and attitudes towards patient-centred communication (Patient Practitioner Orientation Scale (PPOS)). KEY RESULTS: Of participants, 95 % (102) completed the primary outcome measures. Two weeks post-intervention, intervention group participants scored significantly higher on the OPTION scale (adjusted group difference = 18.9, 95 % CI 12.4 to 25.4), ACEPP items (difference = 0.9, 95 % CI 0.5 to 1.3), confidence measure (difference = 13.1, 95 % CI 8.5 to 17.7), and the PPOS sharing subscale (difference = 0.2, 95 % CI 0.1 to 0.5). There was no significant difference for the PPOS caring subscale. CONCLUSIONS: This brief intervention was effective in improving student clinicians' ability, attitude towards, and confidence in shared decision making facilitation. Following further testing of the longer-term effects of this intervention, incorporation of this brief intervention into evidence-based practice courses and workshops should be considered, so that student clinicians graduate with these important skills, which are typically neglected in clinician training.