How can we tell if teenagers are responding to HIV/AIDS awareness campaigns? Is it acceptable to conduct randomised trials in schools to find out? University College London, together with the University Zimbabwe and the London School of Hygiene and Tropical Medicine, looked into the sensitive topic of interviewing and testing teenagers for sexually-transmitted diseases (STDs) including HIV, in a feasibility study for a large community randomised trial. It found that communities in Zimbabwe were enthusiastic about taking part in trials in schools and recognised the importance of these.