Health in the United States is stratified significantly. The stratification in health mirrors broader social inequality, with the socially advantaged generally living longer and healthier lives. While the extreme stratification in health and life expectancy in the United States is well documented, comparatively less research has analyzed how large-scale institutions such as the military and criminal justice system can influence population health and processes of health inequality. Indeed, the military and prisons are especially important for population health and health inequality due to their size, composition of disadvantaged men, high degree of regulation/social control, and ability to shape the life course within the institutions and subsequently. Neighborhoods, are also critically important to shaping health and population health disparities. Thus, the following dissertation analyzes how the military, prisons, and neighborhoods shape population health and health disparities. Using the National Health Interview Survey and the corresponding Linked Mortality file, Chapter 2 shows that black/white inequality in risk of death is smaller among veterans than non-veterans. These findings were net of socioeconomic and behavioral health factors. Additionally, this Chapter shows that the smaller inequality in mortality is concentrated in cohorts who served in the All-Volunteer era. Using the National Health Interview Survey and the Survey of Inmates in State and Correctional Facilities, Chapter 3 shows that the extent to which chronic health conditions vary by educational level is smaller among the incarcerated than non-incarcerated. However, the extent to which infectious diseases differs by educational attainment is significantly larger among the incarcerated population. Chapter 4 uses the Maternal and Infant Health Assessment and the Geographic Research on Well-being study to analyze how long-term neighborhood poverty predicts mother’s reports of their child’s sleep. The findings indicate that children who consistently lived in neighborhoods characterized by long-term high neighborhood poverty had much greater odds of not sleeping the prescribed amount for their age. This was even net of important child, mother, and household characteristics. Overall, the findings stress the importance of considering institutions and neighborhoods when analyzing population health inequality.