This webinar will provide an overview of Serious Mental Illness (SMI) and implications for working affirmatively with transgender and nonbinary clients who have SMI. Background and prevalence of SMI diagnoses among transgender and nonbinary populations will be discussed, including relationships between the experience of gender dysphoria and other mental health symptoms. Common problems and harmful practices will be addressed, along with a case study with suggestions to improve practitioners’ support for TNB clients. The protective role that gender affirmation and gender euphoric experiences can have on behavioral health and long-term well-being will also be explored.