Objective - To describe trends in the prevalence of excess weight (overweight and obesity combined) among middle and high school students in the Val-de-Marne department between 1998 and 2005, as part of a nutritional intervention program. Method - Two cross-sectional studies were conducted on representative samples of middle and high school students in the department. Estimates of overweight and obesity were based on the calculation of body mass index (BMI) according to international thresholds (measured weight and height). Results - The analyses included 1,041 students in 1998 and 960 in 2005, aged 10 to 18 years. The overall prevalence of overweight remained stable between 1998 (16.4%) and 2005 (17.0%), but it increased among children of blue-collar workers (16.4% to 31.1%) and artisans/merchants (14.4% to 26.0%), and decreased when parents held a middle-level professional position (19.1% to 10.9%). It also increased when the father was from a Maghreb country (18.0% to 30.1%) or from an “other” country (outside Europe or the African continent) (13.1% to 23.3%). Multivariate analysis shows that children of manual workers and clerical workers had, regardless of the survey year, a higher risk of being overweight than those of managers. Not observed in 1998, an increased risk emerged in 2005 among children whose father was from the Maghreb (compared to those whose father was from France). Conclusion - The overall prevalence of overweight remained stable between 1998 and 2005. In 2005, differences in prevalence persisted, linked to parents’ occupation, while new differences emerged, associated—as in other European countries—with the father’s geographic origin. (R.A.)