OBJECTIVE To assess the potential association between growth during the first 2 years of life and the risk of overweight in childhood. METHODS Overweight status of 1 582 French children aged 7-9 years in 2000 was estimated, using measured weight and height data collected retrospectively. Overweight was estimated using measured weight and height. Linear mixed models identified six growth parameters associated with later overweight: weight, length and body mass index (BMI) attained at 1 year, average monthly weight and length gain, and average variation in monthly weight gain. RESULTS In the combined logistic regression model, the risk of overweight in boys at 7-9 years was associated with average monthly weight gain (odds ratio [OR] for 100 g=2.06, 95% confidence interval [CI]: 1.22, 3.48) and BMI at 1 year (OR for 1 kg/m(2)=1.83, CI: 1.33, 2.51), while in girls, it was associated with weight at 1 year (OR for 1 kg=2.24, CI: 1.37, 3.66), BMI at 1 year (OR for 1 kg/m(2)=1.58, CI: 1.05, 2.39) and average variation in monthly weight gain (OR for 1 g=1.13, CI: 1.04, 1.22). CONCLUSIONS This study showed the simultaneous association of large infant size at 1 year and early rapid infant growth along with overweight at 7-9 years, as well as involvement of early growth velocity variations. Early infancy, a phase of very rapid growth, constitutes a critical period for the onset of overweight.