It is well documented that the roots of cardiovascular diseases (CVD) are evident in childhood, and elevated levels of serum lipids, blood pressure and body fat are common in childhood. These risk factors are, in turn, related to childhood dietary and physical activity habits. To understand the early development of CVD, it is therefore important to study factors that influence diet and physical activity behaviors in children. Most studies concerned with the determinants of diet and physical activity in children are cross-sectional, limiting their utility for improving understanding of the development of these key health behaviors.