Objectives: To examine which measure of socioeconomic position and socioenvironmental conditions has the strongest relationship with subjective cognitive decline (SCD) among midlife and older lesbian, gay, bisexual, transgender, queer, intersex, asexual, and other sexual and gender minority (LGBTQIA+) adults. Methods: We conducted a cross-sectional analysis of 3869 LGBTQIA+ adults aged 50 years or older participating in a community-engaged survey in California. Using logistic regression, we examined overall associations between each indicator of socioeconomic position and socioenvironmental conditions and SCD. We used a dominance analysis to assess the relative importance of each indicator based on the proportion of variance in SCD it explained. Results: Overall, 14.7% of the sample reported SCD. Midlife and older LGBTQIA+ adults in a lower socioeconomic position (i.e., lower education, unemployment, lower household income, fewer assets, financial insecurity, food insecurity, and unstable housing) had higher odds of SCD than those in a higher position, with significant odds ratios (OR) ranging from 1.44 to 1.93. In contrast, perceiving one's community as safe for LGBTQIA+ people was associated with lower odds of SCD (OR, 0.60; 95% CI, 0.48, 0.76). Dominance analysis indicated that household assets was the most important factor, explaining 2.8% of the variance in SCD (95% CI 2.2%, 3.6%), followed by household income (1.9%; 95% CI 1.2%, 2.7%) and perceived community safety (1.6%; 95% CI 1.1%, 2.3%). Discussion: Supporting the cognitive health of LGBTQIA+ people may require attention to both financial security across the life course and the broader social environments.