This paper is the introductory essay for a set of six papers in which a series of field network evaluation studies, conducted in the United States of America, on the effects of major changes in the grant-in-aid policies and programs of the national government are described. The studies, begun in 1972, focused on the effects of new grant programs on state and local governments and the services they provide. The five studies are of (1) the revenue sharing program, (2) the community development block grant program, (3) all federal grants-in-aid in eleven large cities in 1978, (4) the public service job-creation program, and (5) the cuts and changes in federal grant-in-aid program made under President Reagan. In this paper, the rationale, methodology, and history of these studies are described.