We examined the influence of a professional development intervention on physical education teachers' efficacy. We paired experienced mentor teachers (n = 15) with inexperienced prot¨¦g¨¦ teachers (n = 15) in learning how to teach the Exemplary Physical Education Curriculum (EPEC), a physical activity and fitness focused curriculum. A control group (n = 17) was also included for comparison purposes. We sought to determine if the intervention would increase teachers' efficacy to teach the four EPEC domains (i.e., physical fitness, motor skills, personal and social development, and physical activity and fitness knowledge). Additionally, we anticipated that teachers would enhance their efficacy to overcome four common barriers to physically active lessons. Specifically, we expected teachers to gain confidence in overcoming a lack of space for teaching active lessons, encouraging students who are reluctant to be active, maximizing limited time for active lessons and garnering greater administrative support for providing physically active lessons. A series of Multiple Analyses of Variance analyses indicated a variety of statistically significant results with mean scores in expected directions and small to large effect sizes. For example, for EPEC physical fitness efficacy, there was a significant interaction, (F (2, 44) = 25.10, p<.001, partial eta squared; ¦Ç = .53) indicating a difference among the groups and changes over time. Post hoc tests at the post-test indicated no differences between mentors and prot¨¦g¨¦s but both were significantly different (i.e., higher) than controls. Mean scores showed that both mentors and prot¨¦g¨¦s increased their efficacy whereas controls went down. We found similar results for the remaining scales. In the interest of clarity, we report 2 general conclusions. First, both mentors and prot¨¦g¨¦s increased in their efficacy to teach most of the EPEC objectives and to overcome barriers to teaching physically active lessons. Second, both intervention groups experienced similar gains in efficacy with few differences between the groups. Keyword(s): exercise/fitness/physical activity, physical education PK-12, professional preparation