There has been criticism of systematic reviews and meta-analyses that have shown little evidence of effect of interventions to improve teenage sexual health. Moreover, there is considerable controversy surrounding the validity of outcomes and rigour of design in evaluation methods for communitybased programmes. In this climate, Scotland launched Healthy Respect, one of four communitybased national Demonstration Projects, to address teenage sexual health. Healthy Respect is a complex and multi-stranded intervention in Lothian Region that includes education and healthpromotion activities and alternative ways to provide sexual health services for young people. A multidisciplinary research team at the University of Aberdeen was appointed to undertake an independent evaluation of this demonstration project. Challenging some aspects of theory-based evaluation, it is argued that adopting both quantitative and qualitative methods will provide an understanding of both the context and process of this Health Demonstration Project, as well as tracking outcomes, including behavioural change, in the target population. The authors' evaluation includes: examining the process of implementation; comparative regional mapping of the service context including inter-agency partnership working; and assessing effectiveness using a quasiexperimental design and adjusted, population-based, behavioural and sexual health outcomes. Evaluation from these key perspectives contributes to a balanced appraisal of a complex, community-based health promotion and service delivery intervention.