Researchers currently lack a reliable and valid means of assessing minority stress and resilience factors in transgender and gender-nonconforming (TGNC) people. This study was conducted to develop and evaluate the validity of a tool to better assess these constructs in TGNC populations. The Gender Minority Stress and Resilience (GMSR) measure was developed grounded on Meyer’s minority stress model, and adjusted to reflect the experiences of TGNC populations based on TGNC literature and archival data from TGNC focus groups. The final GMSR includes scales assessing 9 constructs: gender-related discrimination, gender-related rejection, gender-related victimization, nonaffirmation of gender identity, internalized transphobia, negative expectations for future events, nondisclosure, community connectedness, and pride. In the current study, 844 participants completed the GMSR measure as well as measures related to mental health, general life stress, and social support. Results indicated good model fit, criterion validity, convergent validity, and discriminant validity for the 9 hypothesized scales. Discriminant validity for the scales were also partially supported. Overall, the current study offers preliminary evidence of the reliability and validity of the GMSR Measure for use with TGNC populations. The GMSR Measure has several uses for both research and clinical purposes, including increasing understanding of the experiences and correlates of gender minority stress and resilience factors and assessing whether specific therapies or interventions are helpful in reducing risk and supporting resilience in TGNC populations.