Health is an important component of human capital accumulation. An important frontier in the study of health and aging is in the role of social-economic network on the spread of conditions that affect the health of a given individual. For example, in an influential study, Christakis and Fowler (2007) find that changes in the weight of individuals is a predictor of weight changes in their friends. Other important behaviors that may be affected by exploring the structure of the network are not only smoking and teenage pregnancy, but also more positive outcomes such as a routine of frequent physical exercises that may contribute to the quality of life at later stages of the lifecycle. If one can go further and establish potential pathways at the network level, then it becomes possible to devise policies that affect the entire evolution of health over the lifetime, from very early on until much later ages. This type of policy may generate the highest returns not only in pecuniary terms, but also in non-pecuniary terms by increasing longevity and improving quality of life. The main purpose of this project is to contribute to the literature in the estimation of network models and their application to health and human capital accumulation over the entire lifecycle. The project will lay the foundation for subsequent NIH grant proposals on the role of the network in understanding how policies that affect the network configuration or that explores the network configuration to target certain individuals can improve human capital and health over the entire lifecycle.