BACKGROUND/OBJECTIVES: To facilitate the development of practical public health advice targeted at childhood obesity (OB) prevention and make the intervention programs more effective, one has to promote the most protective habits and limit or modify the risk factors. The objective of the present study was to recognize the most important dietary and physical activity habits, sedentary behaviors, plus parental influences that are associated with childhood overweight (OW) and OB, in a nationwide, cross-sectional sample of Greek school children. SUBJECTS/METHODS: Data from 4552 children (10-12 years old) and 2225 of their parents were included in the analysis. Direct anthropometric measurements and information on dietary and physical activity habits was obtained from the children, as was information on parental self-reported anthropometric values, perceptions and family environment information. RESULTS: Multiple logistic regression analysis revealed that the most important predictors of childhood OW/OB were breakfast frequency (odds ratio (OR): 0.95; 95% confidence interval (CI): 0.92-0.97), daily number of meals and snacks (OR: 0.92; 95% CI: 0.87-0.97), the frequency of family meals (OR: 0.86; 95% CI: 0.76-0.99), having both a TV and a PC/video game player in the bedroom (OR: 1.41; 95% CI: 1.18-1.69) and study hours on weekdays (OR: 1.07; 95% CI: 1.02-1.13). In the case of parents, mothers' age (OR: 0.91; 95% CI: 0.86-0.97), maternal (OR: 1.13; 95% CI: 1.06-1.21) and paternal (OR: 1.08; 95% CI: 1.02-1.15) body mass index (BMI) and children's BMI misclassification (OR: 6.22; 95% CI: 3.62-10.71) were significant predictors of children's OW/OB. CONCLUSIONS: These findings could guide future investigations or public health initiatives to prevent and confront the childhood OB epidemic more efficiently.