The U.S. Panel Study of Income Dynamics (PSID) celebrated its 50th anniversary in 2018. Initially designed to assess the nation's progress in combatting poverty, PSID's scope broadened quickly to a variety of topics and fields of inquiry. To date, sociologists are the second-most frequent users of PSID data after economists. Here, we describe the ways in which PSID's history reflects shifts in social science scholarship and funding priorities over half a century, take stock of the most important sociological breakthroughs it facilitated, in particular those relying on the longitudinal structure of the data, and critically assess the unique advantages and limitations of the PSID and surveys like it for today's sociological scholarship.