The paper studies determinants of enrollment onto the Social Security’s DI (Disability Insurance) and SSI (Supplemental Security Income) programs or death before reaching age 65. As individuals age, the homeostatic regulatory mechanism that controls physiological body systems—such as respiratory, cardiovascular, neuroendocrine, immune, and metabolic—becomes more and more frail in its ability to face internal and external stressors. This leads to one-or-comorbid chronic diseases (such as diabetes, cancer, vascular, musculoskeletal, cognitive and mental disorders), DI-qualifying disabilities or death. The speed of progression through these health states depends on the rate of depletion of one’s homeostatic health and frailty levels. Genetic and epigenetic factors comprised of internal and external environments, health care use, health related behavior and cognitive endowments modulate the depletion rate of homeostatic health over life cycle. These, in turn, determine the likelihood of various pathways through the health states. I use the Health and Retirement Study (HRS) data to estimate a multi-state time-to-event model of pathways through these health states. I use bio-markers such as BMI, CES-D, measures of cognitive health, and indicators of health related behaviors such as smoking, drinking, exercising and use of preventative care along the life-course as indicators of latent homeostatic health and frailty levels and how they affect the risks of following various pathways to disability or death before reaching age 65.