['The purpose of this study was to show the association between changes in clinician self-efficacy and readiness to change and implementation of an asthma management program (Easy Breathing).', 'A 36 month randomized, controlled trial was conducted involving 24 pediatric practices (88 clinicians). Randomized clinicians received interventions designed to enhance clinician self-efficacy and readiness to change which were measured at baseline and 3 years. Interventions consisted of an educational toolbox, seminars, teleconferences, mini-fellowships, opinion leader visits, clinician-specific feedback, and pay for performance. The primary outcome was program utilization (number of children enrolled in Easy Breathing/year); secondary outcomes included development of a written treatment plan and severity-appropriate therapy.', 'At baseline, clinicians enrolled 149 ± 147 (mean ± SD) children/clinician/year; 84% of children had a written treatment plan and 77% of plans used severity-appropriate therapy. At baseline, higher self-efficacy scores were associated with greater program utilization (relative rate [RR], 1.34; 95% confidence interval [CI], 1.04-1.72; P = .04) but not treatment plan development (RR, 0.63; 95% CI, 0.29-1.35; P = .23) or anti-inflammatory use (RR, 1.76; 95% CI, 0.92-3.35; P = .09). Intervention clinicians participated in 17 interventions over 36 months. At study end, self-efficacy scores increased in intervention clinicians compared to control clinicians (P = .01) and more clinicians were in an action stage of change (P = .001) but these changes were not associated with changes in primary or secondary outcomes.'] Does improving clinician self-efficacy increase asthma guideline use by primary care clinicians?