TWENTY years ago, a quiet revolution took place in American thinking about the city. Up until then, planners and public officials had generally believed that urban problems could best be mitigated through improvements and additions to the physical equipment of the city: streets, sewers, parks, bridges, subways, civic centers, zoning, housing projects, planned suburbs. But by the early 1960s, with race riots in the larger cities, rapid neighborhood decay, and increasing crime, to think of a city primarily in physical terms seemed naive and inadequate. Social programs to combat poverty and inequality were necessary, and they came in abundance in the 1960s and 1970s. Building projects continued, but the emphasis of planners and politicians had shifted. The great increase in federal aid to cities came in the form of poverty programs, model cities programs, manpower training, community action, and so on. Although some of these social programs still used bricks and mortar, their first targets were poverty and inequality. The education of city planners followed this shift, from studies of physical form to the new social issues, government programs, budgeting and management, and community action. Most architects remained within their traditional craft, but some found mere building an inadequate response to the urban crisis, and turned to social activism instead.