Six pairs of sub-communities (clusters), matched for similar levels of key factors affecting the spread of HIV, will be identified in the vicinity of the Honde Valley. Four of these pairs are likely to be within commercial estates - tea, coffee, forestry and orchards - and two in communal farming areas. Each sub-community will be chosen so that it includes a health clinic where improved STD services can be made available. The behaviour and STD-control intervention will be introduced in one cluster within each pair on a phased basis over a period of twelve months - ie: one new cluster every two months. In each case, a baseline survey for the evaluation will be conducted in the intervention and comparison clusters in the two-month period immediately prior to the introduction of the programme. For the evaluation, 1,000 respondents will be enrolled within a sector of each sub-community following an initial household census - half of those enrolled will be men aged 17-49 years and half will be women aged 15-39 years. Individuals who usually reside in the household will be eligible for full participation in the study - i.e.: recruitment will be on a de jure basis - in order to increase follow-up and reduce within-group heterogeneity. Within a household, the random selection process used will avoid instances where a husband and wife or more than one wife are enrolled and thereby reduce correlation of outcomes within individual clusters. Respondents in each pair of clusters will be surveyed again two years months after the baseline visit. Records will be kept on an anonymous basis but a mechanism will be put in place to enable the data to be linked within and between survey rounds.