Transgender children and adolescents face hardships in all domains of their lives, with many experiencing family rejection, social exclusion, discrimination, bullying and assaults. The mental health implications of these experiences include high rates of depression, anxiety, self-harm and attempted suicide. Gender-affirming social support and medical treatment has been shown to ameliorate the poor mental health outcomes of transgender youth, with those who are supported in their social and medical transition reporting rates of depression and self-worth equivalent to general population levels. Advocacy efforts that improve access to support and medical treatment are therefore likely to produce significant positive health and well-being outcomes for this vulnerable population. The transgender community in Australia identified the legal restrictions placed on children and adolescents accessing medical treatment as a significant barrier to positive psychological well-being. Australian law, unique internationally, required the parents of transgender adolescents to apply for court authorisation prior to the commencement of their child's gender-affirming medical treatment. Concerned by the harm created by this process, a coalition of experts, including transgender children, adolescents and their parents, as well as academic and clinical experts in the fields of law and medicine, was created to advocate for reform. Over a period of approximately 4 years, a collaborative process was undertaken, which ultimately led to law reform and improved access to medical treatment for the transgender community.