The Panel Study of Income Dynamics (PSID) is a nationally representative, longitudinal study of families in the USA that began in 1968. It is the longest-running household panel survey in the world. As of 2015, a total of 39 waves of data have been collected over 47¬ years. The study currently covers nearly 10,000 families and 25,000 individuals and has achieved reinterview response rates of 96‚Äì98% in virtually every wave. PSID interviews collect information on a wide range of economic, demographic, social, and health topics. The study has a genealogical design, and adult children of respondents who split off from their parents to form their own households are recruited into the study. In recent years, PSID has expanded its collection of data on children and young adults through the Child Development Supplement and Transition into Adulthood Supplement, which provide important opportunities to study the early life course. PSID data support research on poverty dynamics and its consequences for individual and family well-being, the intergenerational transmission of human and social capital and health status, and the family and contextual processes surrounding early human capital formation. PSID data and documentation are freely and publicly available on the Internet through the PSID Data Center. Restricted data with geocoded information and administrative data linkages are also available to authorized users under contract. PSID is a unique resource for answering many questions in life course health development research that can be answered with no other data source.