public, coeducational institution of higher learning in Macomb, Illinois, U.S. It was established in 1899 as Western Illinois State Normal School. Instruction began in 1902. The school evolved into a four-year teachers college in 1921. It became Western Illinois State College in 1947 and was elevated to university status in 1957. Total enrollment at the Macomb campus is about 13,000.

The university comprises Colleges of Arts and Sciences, Business and Technology, Education and Human Services, and Fine Arts and Communication. It also includes the School of Extended Studies and the School of Graduate Studies. It offers about 50 bachelor's and more than 30 master's degree programs as well as several preprofessional programs. The university operates a Quad Cities campus in Moline. The Department of Law Enforcement and Justice Administration is the largest law-enforcement program in Illinois. Research facilities include the Frank J. Horn Field Campus, the Illinois Institute for Rural Affairs, and the Alice L. Kibbe Life Science Station on the Mississippi River. Students can also take classes and do research at Shedd Aquarium in Chicago.