Background: Marathon Kids ® (MK) is a community and school-based program that promotes running, walking, and healthy eating in elementary school children. This study assessed the impact of MK on self-reported physical activity (PA), fruit and vegetable consumption (FVC), and related psycho-social factors in a sample of low-income, 4th- and 5th-grade students in Texas (n = 511). Intervention strategies included structured school running time, behavioral tracking, celebratory events, and rewards. Methods: A quasi-experimental design with 5 intervention (MK) and 3 comparison schools was employed. Students were assessed at baseline in the fall and at 3 time points during 2008 to 09. Mixed-effect regression methods were used to model pooled means, adjusting for baseline and sociodemographic variables. Results: MK students reported a higher mean time of running in past 7 days compared with non-MK students (mean = 4.38 vs. 3.83, respectively. P = .002), with a standardized effect size of 0.16. Mean times of FVC ( P = .008), athletic identity self-concept ( P < .001), PA outcome expectations ( P = .007), and PA and FVC self-efficacy ( P < .001 and P = .02, respectively) were also higher in MK students. Fewer differences in social support were observed. Conclusion: Findings provide further evidence on the importance of community and school partnerships for promoting PA and healthy eating in children.