While methods and results of school-based studies have been reported widely in the literature, little published information exists on the practical aspects of recruiting schools and students into a study. This paper reflects on the experiences of a UK-based sexual health survey among 3007 students aged 15-18 years. The survey explored beliefs, attitudes and behaviours in relation to sexual health. This case study highlights significant aspects of planning and conducting successful large-scale research in schools, focusing on the process of conducting the research rather than outcomes. As such, the paper will benefit those intending to sample a school-based population. The key features of effective and feasible research in schools are outlined in four areas: (i) adopting suitable research tools, (ii) selecting and contacting schools, (iii) selecting students within schools and (iv) the importance of fieldworkers. On-site and post-data collection feedback from teachers are incorporated into the discussion of good practice in partnership working with schools and students in research. We conclude by discussing fieldwork experiences and outlining key recommendations for researchers across disciplines engaging in school-based studies.