Relationships between and physicians last a long time at Amsterdam’s Center of Expertise on Gender Dysphoria. Some of today’s adult patients have been visiting the clinic since the age of 5, when their parents first noticed signs of gender dysphoria — the experience of distress that can occur when a person’s gender identity does not match the sex they were assigned at birth. For some very young children, the negative feelings subside with the passage of time and they no longer identify as transgender. But for other children, the distress persists into the years leading up to puberty. These youth can come to the clinic to discuss embarking on a treatment protocol that begins with a diagnostic phase that lasts around six months. During this time, the young people speak with clinicians, fill out questionnaires, and receive mental health support. After that, youth who are interested in a medical transition will be prescribed puberty blockers. From there, they may need to wait a couple of years until becoming eligible for hormones that initiate the development of secondary sex characteristics aligned with their gender identity. At 16, individuals assigned female at birth can get mastectomies. At 18, patients can meet with their physicians to discuss other gender-affirming surgeries, such as hysterectomies, vaginectomies, and phalloplasties (the surgical construction of a penis) for trans men, and vaginoplasties (the surgical construction of a vagina) for trans women. Annelou de Vries, a child and adolescent psychiatrist at the clinic, has worked with hundreds of transgender children, some of whom have gone on to medically transition as adults. Being able to follow them for so long, providing therapy over a course of years, is “an opportunity you usually don’t have in psychiatry,” she said. For many years, the clinic — widely known as “the Dutch clinic” — was one of the few places in the world where children could receive transgender medical care. VU University Medical Center, which has since merged with the Academic Medical Center to create Amsterdam University Medical Centers, originally offered multidisciplinary support to trans adults starting in the 1970s. When a 12-year-old showed up in 1987 and was soon followed by more children, the staff developed its stepwise treatment protocol for teenage patients. De Vries and her colleagues eventually published studies showing the protocol’s effectiveness, and these studies continue to be highly influential, both in the Netherlands and internationally. But pediatric transgender medicine is a new field with a lot of questions yet to be answered by science. What is the long-term impact of blocking puberty on a young person’s health? Can practitioners correctly determine which youngsters will still identify as trans when they are adults? Do the psychological assessments contribute to children’s suffering by delaying access to puberty blockers and hormones? Why has the number of teens coming forward to receive transgender medical care, particularly those assigned female at birth, risen so dramatically in recent years?As researchers attempt to answer these questions, the Dutch clinic’s model, along with similar approaches in the U.S., has faced criticism from all sides. Right-wing politicians, religious conservatives, and some health care associations are calling for medical treatment of teens to be banned or avoided if at all possible; meanwhile, some activists and physicians say the protocol is too slow. They criticize physicians like de Vries and her colleagues for acting as gatekeepers who place unnecessary hurdles on the path of gender transition. The Dutch physicians were pioneers whose work shaped a new understanding of children and adolescents, says Diane Ehrensaft, a developmental and clinical psychologist affiliated with the University of California San Francisco Benioff Children’s Hospitals, where she helped launch the Child and Adolescent Gender Center in 2010. Yet like many U.S. practitioners, when she came across the protocol, Ehrensaft believed that some aspects were overly conservative. In particular, Ehrensaft notes that the Dutch protocol requires children to undergo the first stages of puberty before transition. “We think that potentially puts children through unnecessary distress or trauma to go through a seriously unwanted puberty for the sake of making sure they know who they are,” she said.