AbstractObjective:To assess the coverage of the adolescent weekly iron and folic acid supplementation (WIFS) programme in rural West Bengal, India.Design:We conducted a population-based cross-sectional survey of intended WIFS programme beneficiaries (in-school adolescent girls and boys and out-of-school adolescent girls).Setting:Birbhum Health and Demographic Surveillance System.Participants:A total of 4448 adolescents 10–19 years of age participated in the study.Results:The percentage of adolescents who reported taking four WIFS tablets during the last month as intended by the national programme was 9·4 % among in-school girls, 7·1 % for in-school boys and 2·3 % for out-of-school girls. The low effective coverage was due to the combination of large deficits in WIFS provision and poor adherence. A large proportion of adolescents reported they were not provided any WIFS tablets in the last month: 61·7 % of in-school girls, 73·3 % of in-school boys and 97·1 % of out-of-school girls. In terms of adherence, only 41·6 % of in-school girls, 38·1 % of in-school boys and 47·4 % of out-of-school girls reported that they consumed all WIFS tablets they received. Counselling from teachers, administrators and school staff was the primary reason adolescents reported taking WIFS tablets, whereas the major reasons for non-adherence were lack of perceived benefit, peer suggestion not to take WIFS and a reported history of side effects.Conclusions:The effective coverage of the WIFS programme for in-school adolescents and out-of-school adolescent girls is low in rural Birbhum. Integrated supply- and demand-side strategies appear to be necessary to increase the effective coverage and potential benefits of the WIFS programme.