Hilary Cass, the former president of the Royal College of Paediatrics, has spent the last 3 years collating the evidence for treatment of gender questioning young people; engaging with those young people, their families and their clinicians - all with the aim of improving NHS treatment of this complex and vulnerable group. In this interview, Kamran Abbasi, editor in chief of The BMJ, speaks in depth to Cass about her review - about evidence base for transitioning, but also about the way in which the siloing of care for young trans people has failed them.  They discuss the need to support young people in their journey - Cass is clear that the NHS should allow young people to explore their gender, but that ultimately, that may not mean medical intervention at all.    Reading list The Cass Review - final report The systematic review and meta-analyses published in Archives of Disease in Childhood BMJ Opinion: Gender medicine for children and young people is built on shaky foundations