This dissertation makes three scientific contributions to the understanding of adult health and mortality. The first chapter focuses on the state of Kerala in India, a pioneer in reducing infant and child mortality and life expectancy improvements at birth. However, its life expectancy has stagnated in recent years, with higher male and female mortality among older age groups (60 years and above) offsetting improvements in younger ages. Additionally, the results show that the main contributors to this stagnation are non-communicable diseases (NCDs) and accident/injury-related mortality among 30 to 60-year-old males, highlighting the need for focused policies to address these health challenges and promote further life expectancy gains. The second chapter study examines the experience of child loss among Indian women and men. The results show widespread variation across social groups and socioeconomic status, with parity levels being a major contributor to the observed differences in child loss and that women and men who experience the loss of a child are more likely to be associated with suffering from clinical depression. The study highlights how the demographic dynamics of the past influence the health profiles of current generations. The third chapter analyzes the relationship between socio-economic conditions across the life course and health outcomes in later life among Chilean adults. The study finds that individuals with higher levels of schooling have a lower probability of experiencing multiple functional limitations and lower mortality rates. Females generally outlive males, and disability-free life expectancies vary significantly by gender and schooling levels, with females spending a larger proportion of their additional years living with disabilities than males. The three chapters make substantive contributions to the study of adult health and mortality, and these findings have important implications not only for our understanding of healthy and mortality patterns in India and Chile but also for informing health policy in other countries.