Roberton and Halverson’s (1984) developmental sequences for components of the overarm throw for force is the most valid and reliable developmental tool used to assess overarm throwing in children. However, there is very little biomechanical data on children’s throwing motions and on the actual quantitative differences within developmental levels. The question of whether component level differences actually reflect changes in biomechanical parameters, analogous to their respective component descriptors, has yet to be determined. Therefore, the purpose of this study was to assess overarm throwing motions in children and compare and contrast the results of the developmental component analysis against biomechanical data collected on the same children and asses the predictive validity of trunk, humerus, and forearm levels with respect to their analogous biomechanical parameters. Forty-nine children (34 boys, 15 girls), ages 3-15 participated in the study. Children were tested on three to five maximal effort throws. Trunk, humerus, and forearm action component levels were analyzed using data collected from two 60 Hz video cameras set at perpendicular angles to the thrower. The same throws were also analyzed using three-dimensional high-speed motion analysis (240 Hz) with 16 kinematic parameters quantitatively describing differences in levels of the three components. Dependent parameters were grouped according to their analogous component classification to assess differences between levels and analyzed using three separate MANOVAs. In addition, a stepwise Discriminate Function Analysis (DFA) was used to assess the predictive validity of the component level classifications with respect to differences in their analogous biomechanical parameters. Results of the three MANOVA’s indicated the analogous component biomechanical parameters were significantly different between component levels (Trunk - F(2,44) p < .001; Humerus - F(2,43) p < .001; Forearm - F(2,44) p < .001). The DFA indicated that 97.9% of the trunk component level classifications, 81.3% of the humerus, and 100% of the forearm classifications were correctly categorized with respect to differences in their analogous biomechanical parameters. In general, quantitative biomechanical data agreed with the component classifications of body segment movements and further validates Roberton and Halverson’s developmental component sequences for determining differences in overarm throwing motions.Keyword(s): performance, physical activity, research