This monograph evaluates the equity, adequacy, and efficiency of the Illinois system of school finance. After a brief introduction outlining the purpose and limitations of the study, it first develops two operational definitions of equity, based on disparity measurements and on the association between district spending and local wealth. The results of the equity monitoring are presented in seven tables with corresponding charts for the previous 16 years. The next section similarly begins with operational definitions of educational adequacy, based on comparisons with other states, and follows with an explanation of tables showing Illinois operating expenditure per pupil 1973 through 1986. The final section discusses policy implications of the foregoing fiscal analysis. The conclusion drawn is that Illinois is not equitably funded for K-12 education, and that the situation relative to equity is growing progressively worse. Approximately 400 million new dollars are needed to remedy the situation, and this can only be achieved by raising the personal income tax rate. Notes and references are included, and the tables and charts cited in the text are appended. (TE)