The study will be conducted in the Matlab Health and Demographic Surveillance System (HDSS) field area of the International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B) to determine the population effectiveness of Rotarix in Bangladeshi children. Villages in both intervention and government comparison areas will be included in this evaluation. We propose to introduce Rotarix into half of the villages of the Matlab HDSS. In villages randomized to receive the vaccine, all eligible children will be offered Rotarix during their first two Expanded Programme on Immunization (EPI) visits, as would routinely be done if Rotarix were included in the Government EPI schedule. In villages randomized not to receive Rotarix, children will receive their EPI vaccinations exactly as they would have in the absence of this study. Administration of Rotarix will be conducted by regular EPI staff, but ICDDR,B study staff will be present to document informed consent and collect study-specific information. The Ministry of Health will be an active partner in this evaluation since they will be the agency which may follow up with any subsequent vaccine programme. Vaccination with Rotarix will be recorded on the infant's immunization card which is normally used by the EPI programme, but also on a separate study-specific data collection form.