BACKGROUND:There is an increasing focus on lifestyle as a factor in the pathogenesis of mental health disorders; however, this has been relatively underexplored in child populations. This study aimed to assess the relationships between behavioural lifestyle factors and emotional functioning in a large, population-representative sample of schoolchildren in Greece. METHODS:A representative sample of 2,240 schoolchildren, aged 9-13 years, participated in the Healthy Growth Study during 2007-2010. Emotional functioning was measured using the Dartmouth COOP Functional Health Assessment charts/World Organization of Family Doctors Charts. A score of 3 or higher out of 5 indicated poorer emotional functioning. Participants self-reported dietary intake via three 24-h dietary recalls; fruit, vegetable and soft drink consumption were the dietary variables of interest. Participants' self-reported daily time spent in moderate to vigorous physical activity, and watching TV or playing video games were used to assess physical activity and sedentary behaviour. RESULTS:In fully adjusted models, females were at a greater risk of experiencing impaired emotional functioning compared to males (OR 1.76, 95%CI 1.44, 2.15, p < 0.01). Overweight/obesity compared to normal body weight (OR 1.52, 95%CI 1.31, 1.77, p < 0.01) was associated with poorer emotional functioning. Three hours or more of daily average physical activity compared to less than one hour (OR 0.59, 95%CI 0.40, 0.86, p < 0.01) was associated with improved emotional functioning. Consuming soft drinks compared to non-consumption (OR 1.24, 95%CI 1.02, 1.51) was associated with poorer emotional functioning; this became non-significant after corrections for multiple comparisons were made. Clustering of municipalities was accounted for in all models. CONCLUSIONS:Whilst findings were cross-sectional and causality cannot be inferred, this study highlights the interdependence of emotional and physical functioning in schoolchildren. This points to the potential for targeting shared risk factors for both physical chronic diseases and emotional and mental health conditions among children. Further longitudinal evidence will identify the potential for such shared intervention targets. Adopting a comprehensive, integrated approach to children's emotional, mental, and physical health is warranted.