Object control skills (OCS) provide the means for children to be physically active. In fact, success in OCS in childhood is predictive of performance in adolescence. However, gender equality in some OCS remains elusive. Particularly troublesome is the basic throwing pattern. Some scholars argue that gender differences in throwing are rooting in human evolution. A similar case can be made for sidearm striking that also involves forceful, rapid rotation of pelvis, trunk and shoulders. The purpose of this study was to examine development of throwing and striking at the fundamental movement level. The design was multi-cohort sequential: Boys and girls grades k-8 (N=186) were tested twice per year for five years on the Test of Gross Motor Development (TGMD-2). Children in grades 5-8 (year one) were tested progressively fewer times. Hierarchical linear modeling (HLM) was applied to analyze the data. HLM models change directly, using individual growth curves. As anticipated, significant (p<.001) age-related gains were found for throwing and striking. In terms of gender differences, boys performed better at intercept and slope for throwing (p<.05) and striking (p<.05). Results indicating parallel growth trajectories for boys and girls signify a biological resistance to development of throwing and striking. Specifically, these results reinforce theories that girls may be disadvantaged in skills involving rapid, forceful, segmented pelvic and trunk rotation. Interventions designed to enhance development of throwing and striking should be in place long before grade four when most PE curricula transition to games and sports.