To examine how changes in beliefs during the training process predict adoption of prolonged exposure therapy (PE) by veterans health administration clinicians who received intensive training in this evidence-based treatment. Participants completed a 4-day PE workshop and received expert consultation as they used PE with two or more training cases. Participants were surveyed prior to the workshop, after the workshop, after case consultation (n = 1.034), and 6 months after training (n = 810). Hierarchical regression was used to assess how pre-training factors, and changes in beliefs during different stages of training incrementally predicted post-training intent to use PE and how many patients clinicians were treating with PE 6 months after training. Post-training intent to use PE was high (mean = 6.2, SD = 0.81 on a 1-7 scale), yet most participants treated only 1 or 2 patients at a time with PE. Pre-training factors predicted intent to use and actual use of PE. Changes in beliefs during the workshop had statistically significant yet modest effects on intent and use of PE. Changes in beliefs during case consultation had substantial effects on intent and actual use of PE. Pre-training factors and changes in beliefs during training (especially during case consultation) influence clinicians' adoption of PE. Use of PE was influenced not only by its perceived clinical advantages/disadvantages, but also by contextual factors (working in a PTSD specialty clinic, perceived control over one's schedule, and ability to promote PE to patients and colleagues).