We examine the effect of the transition to a separate middle school after grade six on student cognitive, non-cognitive, and perceptual developments in China. We use an approach that combines inverse propensity score weighting and discrete factor approximation to address the endogeneity of the transition. We find that transitioning students report worse overall development in health, social adaptation and academic achievement and lower evaluation of the school than non-transitioning students. Transitioning students are also less likely to feel confident or popular among peers. The lower performance on the first exam in middle school only partly explains these observed transition effects.