This practical information guide contains eight modules targeted at district and health facility staff, which seek to improve immunization services so as to reach more infants in a sustainable way, building upon the experiences of polio eradication. It includes materials on planning, monitoring and use of data to improve the service which can be used at any level. This 2004 update replaces all previous editions. Topics covered include: target diseases and related vaccines, the cold chain, ensuring safe injections, planning immunization sessions to reach every infant, holding an immunization session, monitoring and using data, and building community support for immunization services.