The increase in prevalence of overweight and obesity is a rapidly growing threat to the health of populations, with it affecting individuals of all ages, including preschool children. Obesity arises from an imbalance of energy intake and energy expenditure, which are influenced by many facts at many levels. Preschool children spend most of their time within the home. This study sought to measure the physical and nutritional characteristics of the home environments of preschool children, through the administration of two newly devised inventories, the Physical Activity and Nutrition Inventories, and explore the relationships between these characteristics and children''s body mass index (BMI) z-score. These two inventories were then correlated with determinants of behaviour, by a food frequency questionnaire and a CSA accelerometer.