Author & Contributor Index
- Illinois State Laboratory of Natural History
- Illinois State Library, Illinois Heritage Association
- Illinois State Museum
- Illinois State Natural History Survey
- ILLINOIS STATE NATURAL HISTORY SURVEY
- Illinois State Toll Highway Authority
- Illinois State University
- Illinois State University. Department of Geography-Geology
- Illinois State Water Survey
- Illinois State Water Survey,
- Illinois State Water Survey Center for Watershed Science
- Illinois State Water Survey. Chemistry and Hydrology Divisions
- Illinois State Water Survey Division
- Illinois State Water Survey, Hydrology Division
- Illinois State Water Survey. Office of Sediment and Wetland Studies
- Illinois State Water Survey Surface Water Hydrology and Hydraulics Section
- Illinois State Water Survey, Water Quality Section
- Illinois State Water Survey. Watershed Science Section.
- Illinois Sustainable Technology Center
- Illinois Terrorism Task Force
- Illinois. The Division of Highways
- Illinois Transportation Archaeological Research Program
- Illinois. University. Department of Household Science
- Illinois. University. Engineering Experiment Station
- Illinois. University. Extension Service in Agriculture and Home Economics
- Illinois Waste Management and Research Center
- Illinois. Waste Management and Research Center
- Illinois Waste Management and Research Center (WMRC)
- Illinois Waste Management Research Center
- Illinois Wesleyan University
- Illinois. Zoning Laws Study Commission
- Illiois Heritage Association
- Illiois State Academy of Science
- Illlinois State Water Survey,
- Illustration: Bernardi, Lucia
- Illyes, Robert F.
- ILO Subregional Office for Central and Eastern Europe
- Ilseman, Michael
- Ilundain-Agurruza, Jesus Maria
- Ilusby, Ralph D.
- Ilyas, Ihab F.
- Ilyas, Mohammad Bashir
- Ilyushin, V.
- Imaad, Syed M.
- Imai, Brian
- Imai, Mutsumi
- Imane, Haykal
- Imarenezor, Osazomon
- Imbeault, Fernand Adelard
- Imberman, Angela