The data used in this report to present three statistical pictures of Illinois public libraries during the fiscal year 1987-1988 comes primarily from the 1987-88 Illinois public library annual report forms. Section One presents the individual view of public library operations in which facts about use, resources, and finances are provided. Tables are used to present these facts. In Section Two libraries are grouped by size of population served, and statistical averages and percentiles for libraries serving populations of different sizes are presented. Tables showing selected aspects of library operations are listed for individual libraries in each population group in this section. In Section Three libraries are grouped by system, and data are reported in statistical averages and percentiles for library systems. Selected aspects of operations are listed for individual libraries and charts that compare the individual systems are found in this section. Three types of facts about library operations are also presented in this report: (1) basic statistics, e.g., the total circulation or number of books held; (2) ratios, e.g., the number of circulation transactions per capita; and (3) percentages, e.g., the percentage of its total operating budget that a library spends on books. (MAB)