The case study titled “CDD-WATSAN Project in Medinipur – An Assessment, 1991-2001” has been developed and published in 2004 by United Nations Children's Fund (UNICEF). This paper discusses the Control of Diarrhoeal Diseases-Water Sanitation (CDD-WATSAN) project carried out since 1991 in the district of Medinipur, West Bengal. A comparison of three studies — baseline, mid-term review and the final impact assessment — is presented. The key parameters considered were the use of water and sanitary facilities within households and primary schools, and improved hygiene practices at home.