This volume provides fundamental and evidence-based information on working with transgender and gender diverse people in mental health services. The authors, who are experts in the field, outline the key qualities of affirming mental health services, as well as explore strategies for improving inclusivity and what evidence-based care with trans clients looks like. They also provide insight into current topics, such as working with youth, the harmful and ill-advised approach known as rapid onset gender dysphoria, and whether and how autism is a co-occurring diagnostic concern. Practitioners will find the printable resources provided invaluable for their clinical practice, including sample letters of support for trans clients who are seeking gender affirming medical care.