This toolkit draws on the expertise ofpublic health practitioners who have experience with publichealth surveillance and who have recognized the core role ofsurveillance in public health. These practitioners haveadvocated for surveillance programs, supplied innovativeideas, and provided insightful critiques over many years.This toolkit also draws on the experience of Bank staff andtechnical experts from the PAHO and the CDC who havecontributed to Bank missions. The toolkit also makes use ofWHO references, primarily those from the WHO s Web site.Part A of this toolkit provides some theoretical concepts,and knowledge about surveillance that has been gainedthrough applying these concepts and the practice ofsurveillance in developing countries. Part B providesinformation that will be useful to Task Managers as theyprepare loans for strengthening public health surveillancesystems. Several World Bank experiences are shared. Thefocus of part B is on practical aspects of surveillance andon lessons learned.