Elementary school age children engage in levels of physical activity that are well below recommended guidelines. It has been suggested that classroom teachers can assist in remedying the problem by providing physical activity breaks and physical activity embedded in instruction. This study utilized the instrument, Physical Activity in the Classroom, to investigate the level of physical activity used in classrooms and to discover whether teachers differed in the amount of activity based on grade level and their own perceived level of personal fitness. It explored academic and behavioral benefits related to incorporating physical activity in the classroom and discovered what supports teachers report they need to incorporate more physical activity during the school day. The 31-item instrument was tested on a random cluster sample of 393 K-5 elementary school teachers Findings revealed that teachers incorporated low levels of physical activity during their lessons. Math was identified as the subject area where they are most likely to incorporate a physical activity component. The K-5 teachers endorsed academic and behavioral benefits of including physical activity throughout the school day. They maintained willingness to accept responsibility for including more physical activity but need support from administration and professional development to accomplish the goal. A factor analysis of the study instrument indicated that further refinement is needed to improve construct validity. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]