Research has shown that the prevalence of overweight in recent immigrants increases with time spent in North America; however, there is a lack of research on overweight in Canadian immigrant youth. The purpose of the current study was to assess the relationship between generatio!1 of immigration and overweight in Canadian youth, and to examine the influence of various risk factors (acculturation, ethnicity, socioeconomic status) on this relationship. Longitudinal data from Cycles 1 to 7 of the National Longitudinal Survey of Children and Youth were used. Children aged 6-11 years ( N = 13,657) and adolescents aged 12-17 years (N = 10,467) were included. Generation of immigration was classified based on youth and parents' countries of birth. Overweight was assessed using age- and sex-specific percentiles, based on parent- and self-reported body mass index. Multilevel modeling was used to test hypotheses. Results showed that generation of immigration predicted overweight in both children and adolescents, after controlling for gender, age, socioeconomic status, and ethnicity. First generation immigrants showed relative weight gain between childhood and adolescence. The effects of acculturation on overweight depended on generation of immigration. This research suggests that consideration of generation of immigration and the acculturation process are important for obesity prevention strategies in Canadian youth.