The Healthy Young Adults Transitions (HYAT) project was set up to engage a diverse group of young service users (16-25) from across England in a process that identifies what they and their peers see as good practice in key health services for young people - sexual health & relationships, substance misuse and mental health & well-being. The group consulted with over 600 young people on their experiences and perceptions of these three youth oriented health services. They demonstrated that seeking out, representing and responding to the views of young people is an effective way of supporting health services, especially in the transition from child to adult services. This lively report presents their findings and recommendations - including their list of the 'essentials of youth involvement' - which were shared with professionals, agencies and students in the relevant fields.