A Volunteer Lake Monitoring Program initiated by the Illinois EPA in 1981 was continued in 1991. Citizens were trained to measure Secchi disc transparency, total depth, and record field observations from a boat at designated sites on their chosen lake. Readings were to be taken at least twice a month from May through October, and the results forwarded to the Agency. In addition, volunteers for 41 lakes collected water samples for analysis of nutrients and suspended solids when performing the Secchi monitoring. This report provides a historical perspective of the Volunteer Lake Monitoring Program and describes program objectives and rationale. Methods for volunteer training and data handling/analysis are described; 1991 program results presented and discussed; and trends analyzed.