In investigating the association between the school lunch programs and children's body weight, this study focuses on the school lunch programs in Taiwan. Using a national representative dataset of elementary schoolchildren, we estimate a mixed multinomial logit model to cope with the potential endogeneity issue, and examine how different types of food preparations for school meal programs may affect children's weight in different ways. The results indicate that children who go to schools which serve lunch meals prepared by school kitchens tend to have lower weight on average. In contrast, children who go to schools offering lunch boxes purchased from outside restaurants tend to have higher weight on average. From a policy standard point of view, our findings could shed some light on how school lunch policy can be designed to help prevent children's obesity.