The prevalence of overweight children age 6 to 11 has more than doubled in the past 20 years in the United States (Ogden, Carroll, McDowell, Tabak, & Flegal, 2006). These statistics clearly show an epidemic of childhood obesity in the United States and has forced policy makers, administrators, educators, and parents to take notice. The purpose of this study was to examine the effects of a professional development (PD) intervention on the physical activity (PA) levels and fitness of 4th and 5th grade students. Twenty-one physical education teachers in 14 elementary schools participated in the study. Physical education teachers where involved in PD opportunities (full day trainings, PD on-site visits, feedback on lessons, sharing of students activity and MVPA data, and goal setting challenges). Data collected (mixed method) for this project extended over a six month period and included field notes from live teacher observations, video-taped lessons, formal interviews, School Health Index, teacher survey, lesson plans, and SPARK PE activity logs. Video-taped lessons were analyzed using three instruments: SOFIT, an instruction, activity, and management time coding instrument, and SPARK PE quality assessment. Results of this study revealed that the PD intervention had a positive impact on the amount of student PA and MVPA time students received in physical education. The PD staff development and on-site visits were helpful in closing the student “activity gap” between Title I and Non-Title I physical education classes. As a result of the intervention teachers became more aware of the importance of promoting student PA during and beyond their classes. Weekly progress reports, sharing Time Analysis and SOFIT data with teachers, individual goal setting, collaboration with other colleagues, PD on-site support and follow-up were found to be reasons why teachers were able to make a positive change in increasing students PA levels. Teachers' reported that they liked how the PD program challenged them to think about their teaching, and liked the activities in the SPARK PE curriculum. Teachers listed time, space and facilities, and support as barriers they faced when trying to increase student PA during and beyond physical education class. Results from the FITNESSGRAM (n=495) data showed improvement on 3 of the 7 fitness measures (mile run, push-ups, trunk lift). While normal adolescent development may have contributed to these increases, qualitative data suggest that the PD had an impact on teachers increasing their curriculum focus on student fitness. Keyword(s): elementary issues, exercise/fitness/physical activity, physical education PK-12