Abstract Objectives The purpose of this study was to examine disparities in mental health and the social determinants of health (SDoH) among privately insured transgender and gender minority (TGM) patients in the United States. Methods Data came from FAIR Health, a repository of private health insurance claims data covering over 150 million individuals in the United States. TGM patients (n = 274,479) were identified with medical claims that included a diagnosis for gender dysphoria or gender identity disorder. A random 5% selection of cisgender patients (n = 7,456,823) was used as a comparison group. We estimated descriptive statistics and used multivariable logistic regression models to compare health outcomes between TGM and cisgender patients. Results TGM patients were more likely to have anxiety (odds ratio [OR]=7.02; 95% confidence interval [CI]=6.94-7.09), depression (OR = 9.27; 95% CI = 9.16-9.37), post-traumatic stress disorder (OR = 9.03; 95% CI = 8.86-9.21), and substance use disorder (OR = 2.93; 95% CI = 2.86-3.00) compared to their cisgender peers. TGM patients were also more likely to have problems with education and literacy (OR = 5.95; 95% CI = 5.64-6.28), employment (OR = 3.67; 95% CI = 3.44-3.92), economic circumstances (OR = 5.74; 95% CI = 5.39-6.12), and social exclusion (OR = 7.35; 95% CI = 6.91-7.81). Compared to TGM patients living in states with transphobic policy environments, TGM patients in states with comprehensive protections from discrimination fared better. Conclusions We found wide disparities in mental health and the SDoH among privately insured TGM. More research is critically needed to better understand the health and social needs of TGM populations. Meanwhile, policymakers should consider enacting policies that would prohibit discrimination against TGM people throughout the SDoH -- or the conditions where we live, learn, work, play, and age. Health care providers should also receive education on the unique health needs of TGM patients to advance health equity.