The economics literature on the determinants of diarrhoea focuses on infants; but what about school going adolescents? Our survey in an Indian village school affirms that sanitation, defecation practices at home and school, and the degree of crowding of living space at home are all significant determinants of diarrhoeal incidence for adolescents. Usage of toilets at school varies as a function of gender and existence of a toilet in student’s home. Access to toilets is not sufficient to guarantee their usage. To eliminate open defecation: toilets installation, behavioural change, and sustainable mechanisms to maintain school toilets seem necessary. © 2017 Informa UK Limited, trading as Taylor & Francis Group.