Gender diversity refers to gender expressions and/or gender identity experiences that vary from the common experiences of gender. Gender-diverse people may be gender nonconforming, gender nonbinary, gender fluid, gender exploring, transgender, and so forth. Some gender-diverse individuals experience gender dysphoria and/or gender incongruence and may require gender-affirming supports, including gender-affirming medical interventions. The co-occurrence of autism and gender diversity has been highlighted in a series of studies internationally as well as through rich community expressions. Studies in gender-referred individuals reveal high rates of autism traits as well as high rates of existing autism diagnoses. Studies in autistic populations reveal greater gender diversity characteristics. The long-term course of gender diversity in autistic individuals is poorly understood. Clinical guidelines have been developed for adolescents with the co-occurrence, but much work remains: No gender-related measures have been developed and tested for use in neurodiverse populations, no programs exist to support gender-diverse neurodiverse adults, and little is known about co-occurring mental health profiles, risks, or protective factors for people with the co-occurrence. The inclusion of this chapter on co-occurring autism and gender diversity within a book on “co-occurring psychiatric conditions” is problematic, because gender diversity is not a “psychiatric condition,” but instead a form of human diversity. The diagnosis of Gender Dysphoria is useful only insomuch as it allows individuals to obtain necessary gender-related supports. The authors’ choice to include this chapter in this book reflects a compromise, motivated by the need for educating both autism and gender specialists in this common co-occurrence.