The Panel Study of Income Dynamics (PSID) is a longitudinal survey of a nationally-representative sample of U.S. families that began in 1968. With data have collected on the same families and their descendants for 41 waves over 51 years, and with two major immigrant refresher samples added in 1997?1999 and 2017?2019, PSID can justifiably be considered a cornerstone for empirical social and behavioral research. PSID provides long-term measurement, over the life course and across generations, of economic, social, demographic, and health processes, which has inspired researchers to investigate the dynamics of these processes and their inter-relationships. The enormous range of research opportunities provided by the PSID data has led to PSID be-coming one of the most widely used social science data sets in the world. NICHD has co-funded the collection of the biennial Core PSID interview for each of the nine waves that were fielded from 2003 to 2019 and NICHD also fully funded the 2017?2019 immigrant refresher. This project will build upon this investment through the following three specific aims: First, to collect data on three modules?family dynamics, fertility and newborns, and education?as part of the 2021 round of the Core PSID survey. Second, to design and field in 2021 a new module to collect information on assimilation among immigrant families. Third, to clean, document, and distrib-uted these data free of charge through the PSID Online Data Center, provide continuing outreach and support to new and established data users, and encourage new research using PSID data through a small grant compe-tition. This project will make several major contributions. It will extend the longest-running household panel sur-vey in the world, thereby maintaining PSID as a premier data source for studying family dynamics, investments in children, and wellbeing over the life course, across generations, and over time for the entire U.S. population. By continuing the collection of enhanced data on educational attainment, this project will support more detailed analyses of the determinants of schooling decisions within the family context. The on-going collection of the PSID newborn module will significantly expand the available information on early life outcomes, which, in turn, will enhance the value of PSID for studying birth outcomes and for investigating the consequence of birth out-comes and very-early life experiences for subsequent life course outcomes. By continuing data collection on the dynamic processes of family formation and dissolution, fertility, and living arrangements, this project will al-low researchers to understand the evolving complexity and circumstances of families in the U.S. The collection of new data on immigrant assimilation will support new and innovative analyses of adaptation and integration of the latest cohort of immigrants to the U.S., as well as comparisons with earlier immigrant cohorts. Finally, out-reach to and support of data users, and the implementation of a small grant competition, will maximize the past and current investments in collecting Core PSID.