Current trends in population growth, aging population, and improved medical care with concomitant increased survival rates foretell increased prevalence of chronic conditions across all populations. Two theories have been posited regarding aging, disparity, and chronic condition prevalence. Compression of morbidity theory suggests that as one grows old, the disparity gap narrows since only the hardiest individuals survive. In essence, mortality drives this narrowing or elimination of health disparities among disadvantaged minority groups in old age. Establishing prevalence of chronic conditions over the life course among gender and sexual minority (GSM) groups compared to cisgender heterosexual groups can provide support for either or both of these theories, depending on the outcome and results. This chapter describes the prevalence of four chronic conditions: hypertension/cardiovascular disease, asthma, diabetes, and self-reported poor health among GSM as compared to cisgender heterosexual populations. It presents a review of the literature comparing GSM to cisgender heterosexual participants.