Book excerpt: Defining importance of diseases; FAO/EMPRES: a new emphasis; Early detection; The need for surveillance; What is surveillance?; Surveillance on the ground; Putting a surveilance system in place; Surveillance for what?; Surveillance when and how?; Surveillance in resource-poor countries; Information systems; Setting the goals; Determining needs and outputs; Computerisation; Questionnaire design; Databases; Data quality control; Feedback; The role of GIS; Motivating and training field staff; Awareness creation among decision-makers; Using surveillance as a management tool; FAO involvement in surveillance and information systems development; Examples of questionnaires.