The growing importance of the evidence-based movement has made experimental evaluation a key issue among researchers, practitioners, commissioners and policy makers. However, experimental evaluation remains controversial in the sexual health field. This partly reflects the diversity ofgroups involved in this area and their different views on the most appropriate research methods. This book provides an analysis of the methodological and practical issues involved in evaluating sexual health interventions. The book will appeal to trial enthusiasts through discussion of specific issues in trial design, and also to those with a sceptical interest in the potential of experimentation and its appropriateness or feasibility. It is concerned with methodology rather than the substantive findings of research, and considers the requirements of research in both developed and developing countries. The focus of the book is on sexual health interventions, although many of the issues are equally applicable to other areas of behavioral and social research.