Declines in physical activity (PA) and increases in obesity levels in children have prompted increasing interest in understanding children’s PA behavior. The mastery of fundamental movement skills (FMS) is a potential correlate of the involvement of children’s participation in PA as stated in the Surgeon General’s Report (1996) and in the Youth Physical Activity Promotion Model (Welk 1999). This research study investigated the relationship between FMS and PA in second grade children. It is hypothesized that a positive moderate correlation exists between FMS and PA. Body mass index (BMI) was tested as a moderator of the relationship of FMS and PA. The study investigated the associations among total FMS, manipulative skills, locomotor skills, habitual PA, organized PA, sedentary behavior, and BMI for males and females. To assess FMS a process-oriented technique was used. Mann-Whitney and t-tests were used to test for gender differences and Spearman correlations, and Hierarchical Regression analyses were used to test relationships. Gender differences were observed for total FMS, manipulative skills, and step count, therefore further analyses were conducted separately for males and females. The strength of the relationship of FMS and PA in second grade children in this study was gender and skill specific. Habitual PA was positively correlated with total FMS and manipulative skills for males. No significant correlations were found for females. The organized PA was positively correlated with total FMS for males and females and locomotor skills for females. BMI was not a moderator of the correlations of habitual PA and FMS. These results expanded previous research conducted with product-oriented FMS assessments in elementary school children. Results of this study are important for PE teachers and parents. Physical education and physical activity intervention programs must target motor skill development, especially the manipulative skills, which appears to be needed for increasing children’s PA behavior.