OBJECTIVE: To explore possible links between adherence to the Mediterranean Diet (MeD), excess body weight, energy balance behaviors, and academic performance in Greek primary schoolchildren. DESIGN: Cross-sectional study. SETTING: Primary schools in Athens, Greece. PARTICIPANTS: A total of 528 students (256 boys and 272 girls), 10-12 years of age, were recruited from 21 primary schools in the area of Athens, Greece. MAIN OUTCOME MEASURES: Students completed a specifically designed energy balance behaviors questionnaire together with the KIDMED index, which evaluates the degree of adherence to the MeD. The teacher assessed academic performance through a specifically designed, 5-scale questionnaire. Standard anthropometric measurements were also taken. ANALYSIS: Block stepwise regression analysis was conducted. RESULTS: Adherence to the MeD (β = .140; P = .001), obesity (β = -.095; P = .001), physical activity levels (β = .206; P = .001), hours of sleep (β = .100; P = .003), television viewing (β = -.068; P = .05), and global self-esteem levels (β = .122; P = .001) are significant factors in predicting academic performance in primary schoolchildren. CONCLUSIONS AND IMPLICATIONS: Poor adherence to the MeD, obesity, and low physical activity levels seem to negatively affect academic performance in children. Understanding these interrelationships could facilitate the formation of policies focused on improving children's academic achievement.