We study the effects of Canadian Indian residential schooling on two anthropometric measures of health during childhood: adult height and body weight. We use repeated cross sectional data from the 1991 and 2001 Aboriginal Peoples Survey and leverage detailed historical data on school closures and location to make causal inferences. We find evidence that, on average, residential schooling increases adult height and the likelihood of a healthy adult body weight for those who attended. These effects are concentrated after the 1950s when the schools were subject to tighter health regulations and students were selected to attend residential school based partly on their need for medical care that was otherwise unavailable. Residential schooling is only one policy in Canada that impacted status First Nations peoples’ health, so our results must be understood in the broader social context. Taken in context, our results suggest that health interventions in later childhood can have significant impacts on adult health. We also document significant increases in height and body weight for status people born after the 1960s, suggesting substantial changes in diet and living conditions during this time period.