To identify key components of a specialist teenager and young adult (TYA) cancer unit from the perspective of young people and health professionals. A facilitated workshop was held in England at which participants prioritized 15 core features of a specialist cancer unit identified in a literature review. Themes were transferred onto cards and organized using a pyramid. Notes were made of the discussion and how decisions were reached. The exercise was repeated in a survey at a patient conference. Data were analyzed by weighting the ranked position and by content analysis. Eleven young people and 22 health professionals attended the workshops, and 64 young people completed the survey. Young people's top three priorities were a dedicated unit, contact with peers, and provision for partners/parents to live in the unit with them. Health professionals prioritized best chance of survival and best quality of life, access to expertise, access to computers/Internet, and age-appropriate equipment. Priorities varied across and within healthcare professionals and young people, and were dependent on viewpoint and personal experience. This is an essential first step toward a fuller description of the benefit of specialist TYA cancer services and highlights the importance of consulting users in service development.