MARCH 2006 — This document is part of a wider series of guidance on HIV, STI and behavioural surveillance (collectively known as Second Generation Surveillance) and population size estimation, developed over the last decade by UNAIDS, the World Health Organisation and their many partners in surveillance. One of the goals of this series is to ensure that surveillance data get used extensively in managing HIV prevention programmes at the local level and in planning, managing and evaluating HIV prevention and care programmes at the national level.