Background: Fundamental movements (FM) of children influence the willingness to engage in physical activity (PA). Thus, proper FM skills are the foundation for a lifespan of PA. Objective: This study examined what factors may affect children’s PA in relation to FM pattern capabilities. Methods: The study examined the influence of SES when three low-income schools were provided additional PA opportunities on days PE was not taught. FM patterns in relation to object control (OC) and locomotor skill (LC) development were evaluated on K (n = 871), 1st (n = 893), and 2nd graders (n = 829) using the Test of Gross Motor Development-2 (TGMD-2) instrument (Ulrich, 2000). Schools were dichotomized and categorized as being low SES (n = 2008) and high SES (n = 578) status. Results: A significant relationship was revealed with LC (r = 0.264; p = 0.001), OC (r = 0.171; p = 0.001), and total TGMD-2 (r = 0.264; p = 0.001). Low and high SES schools significantly improved overall TGMD-2 scores. High SES schools children were significantly higher in LC [F, (2, 1272) = 29.31, p = 0.001], OC [F, (2, 1272) = 23.14, p = 0.001], and total TGMD-2 [F, (1, 1272) = 38.11, p = 0.001]. Conclusion: Low SES schools need to concentrate on PA-based activities to engage students in FM patterns, to help narrow the gap in FM capabilities. In addition, the increase in PA opportunities for lower SES schools could positively impact brain function, cardiovascular fitness, and overall well-being.