The primary focus on the overall higher risk for poor psychosocial and health outcomes has overshadowed inquiries into general psychological processes that might support the psychological well-being of transgender and nonbinary individuals (TNB). Using self-determination theory to assess basic psychological needs (BPN) satisfaction and recent findings about the importance of authenticity to TNB people, we tested the hypothesis that general authenticity would explain positive associations between perceptions of BPN satisfaction and eudaimonic well-being (EWB). We recruited a TNB sample of 489 adults ages 18-61 (M = 26.32, SD = 6.72) who completed a Qualtrics survey hosted on the Prolific Academic platform in 2022. The results of structural equation modeling supported the hypothesized model; people who reported higher levels of BPN satisfaction also reported significantly higher EWB. Higher levels of authenticity partially, but not completely, explained this association. Self-determination theory may be a useful theoretical framework for further understanding barriers and facilitators of TNB adults' EWB. In the social context of stigma and discrimination, being more authentic helps facilitate one's BPN satisfaction and thereby supports EWB. These findings have implications for future testing of general psychological processes in the TNB population and interventions to facilitate basic needs satisfaction. (PsycInfo Database Record (c) 2025 APA, all rights reserved).