This paper is primarily concerned with identifying and explicating the environmental forces and political factors responsible for legislative enactment of major school finance changes in Wisconsin in 1973. Easton's political systems theory serves as a conceptual framework for the study. In addition, Lindblom's leadership model, Truman's interest group theory, and Wahlke's legislative role theory model are also used to focus on different aspects of the school finance policymaking process. System inputs responsible for the new finance formula are categorized as changes within the legislature's environment and changes within the legislature. Identified environmental inputs include citizen's demands for property tax relief, judicial pressures for school financing changes, and the state's revenue windfall. Major demand articulators include Wisconsin's governor, the Democratic party, and several organized groups within the state. Legislative inputs include the Democratic majority in the assembly and the Democratic majority on the joint finance committee. In conclusion, six hypotheses are formulated and discussed based on what actually occurred in Wisconsin. (Author/JG)