The purpose of this study was to examine the effects of a school-based plyometric training program (i.e., Plyo Play) on children's fitness performance. Forty children (8 to 11 yrs) participated in the program and 34 age-matched children served as controls. Performance of the long jump, sit and reach flexibility, abdominal curl, push-up, shuttle run, and half mile run was assessed at baseline and post-training. Children who participated in the program made significantly greater improvements than controls in the long jump (7.9 [plus or minus] 17.3 cm vs. -0.3 [plus or minus] 8.4 cm) push-up (4.1 [plus or minus] 6.1 vs. 1.1 [plus or minus] 5.2), and half mile run (-52.1 [plus or minus] 68.7 sec. vs -10.5 [plus or minus] 50.8 sec.). These data indicate that plyometric training can enhance selected measures of lower body power, upper body strength, and aerobic fitness in children. (Contains 3 tables.)