The Philadelphia Social History Project (PSHP), now in its seventh year of research, seeks to deepen our understanding of the micro-level workings and consequences of urbanization and industrialization. To accomplish this task it has converted to machine-readable form a vast body of historical information describing the 2.5 million persons who lived in Philadelphia in the years 1850, 1860, 1870 and 1880 as well as their careers, housing, businesses, manufacturing firms and transportation facilities. The PSHP serves as the umbrella organization for an interdisciplinary team of pre- and post-doctoral scholars from sociology, economics, demography, geography, social work and city and regional planning as well as from history. The PSHP proposes four research areas. "The Nature of Work" is concerned with how changes in scale, productivity, mechanization and the organization of work shuffled the occupational universe and affected the opportunity structure. "The Uses of Urban Space" focuses on the process of spatial differentiation which gradually transformed Philadelphia from its colonial/commercial character of compactness and heterogeneity in residence, business and industry to its modern/industrial character of decentralized sprawl, sharp segregation in residence, and distinct zones of commerce and industry. "Life-Course Developments" studies the timing and sequencing of consequential individual-level decisions and events by arraying them in "careers," e.g., in jobs, residence, family. Special Group Experiences" examines Blacks, Irish, and Germans, the "Aristocracy of Labor," the Poor, Welfare Recipients, Criminals and Women in order to learn how, in a context of rapid urbanization and industrialization, work, migration, social and residential mobility, assimilation, family behavior, fertility and mortality were mediated by the four major differentiators of experience: race, ethnicity, class and sex.