Worldwide the population of older adults is growing in complexity and diversity, including by sexual orientation and gender identity. Based on an innovative life course equity framework, this study reveals new cutting-edge findings on the interplay between marginalization, identity, health behaviors, quality of life and health of lesbian, gay, bisexual, and transgender (LGBT) older adults, and assesses key differences by sex and age group. Based on three most recent waves of longitudinal data (N = 2,450) from Aging with Pride: National Health, Aging, and Sexuality/Gender Study (NHAS), this study applied fixed effect models examining within-subject changes in experiences of discrimination, identity stigma and affirmation, and health behaviors over time on quality of life and cognitive and functional impairment. Within-subject increases in day-to-day discrimination, identity stigma, and poor nutrition across time points predicted lower levels of physical, psychological, social, and environmental QOL. Within-subject increases in day-to-day discrimination and poor nutrition and decreases in physical activity predicted higher levels of cognitive and functional impairment, while an increase in microaggresions and decrease in identity affirmation predicted higher levels of cognitive impairment. Gender and generational differences were found. Change in day-to-day discrimination had a greater impact on men; poor nutrition had a greater impact on the oldest old. As the population ages, it is imperative to identify groups at highest risk and those aging well to ascertain modifiable mechanisms so that global research, practices, and policies can be tailored to improve the health and well-being of our growing worldwide demographically diverse older adult population.