The aims of this study were, first, to identify current forms of school-based sexual health services (SBSHS) and school-linked sexual health services (SLSHS) in the UK; second, to review and synthesise existing evidence from qualitative and quantitative studies concerning the effectiveness, acceptability and cost-effectiveness of these types of service, and third, to identify potential areas for further research. The study had two components. The first, the service mapping component, was based on a postal questionnaire circulated to school nurses in all parts of the UK (gaining a response rate of 14.6%), and on semistructured telephone interviews with 51 service coordinators in NHS and local authority (LA) roles. Quantitative data from the questionnaire were analysed with the use of spss, primarily to produce descriptive statistics relating to staffing and facilities offered. Qualitative data from questionnaire free text sections and from interviews were subject to thematic analyses. The second component was an evidence synthesis, based on a three-part systematic review: a review of quantitative evidence about service effectiveness; a review of qualitative evidence about user and professional views; and a mixed-methods synthesis. Electronic databases were searched from 1985 onwards, and all literature searches were performed in January 2008. Cost-effectiveness modelling was not carried out because insufficient data were available to support it.