Ohio Northern University

Henry Solomon Lehr founded the "Northwestern Ohio Normal School" in August 1871. When the college's curriculum grew to include pharmacy, engineering, law and business programs, its name was changed to "Ohio Normal University" in 1885 and, eventually, in 1903, to Ohio Northern University. In 1899, it became affiliated with the United Methodist Church to reduce debt.

Before the Great Depression, more than one thousand students were typically enrolled at Ohio Northern every year. Both the Great Depression and the following World War II plunged the school into low enrollment, and the possibility of closure was considered. During World War II, enrollment reached a low of 156 students. Thanks to the G.I. Bill, Ohio Northern was able to bring enrollment back up to nine hundred students by 1946.

Throughout the 1960s, a number of ONU students and faculty/staff participated in the American Civil Rights Movement. ONU hosted Dr. Martin Luther King Jr. on January 11, 1968, four days before his 39th birthday and just three months before his assassination. During his visit at ONU, King famously spoke regarding the myth that many immigrant and/or ethnic groups successfully pulled themselves up by their bootstraps, whereas African Americans were incapable of doing so. ONU honored King and his speech on campus with the unveiling of a statue in his likeness on April 17, 2018.

Growth continued under DeBow Freed through the 1980s and 1990s with additions to the Taggart Law Library, Presser Hall, Dukes Memorial, Wilson Art Building, Biggs Engineering, Heterick Memorial Library, and Meyer Hall of Science, and the construction of the Freed Center for the Performing Arts and a new president's on-campus home. Under Kendall Baker, campus additions include Dicke Hall, an expansion of the Robertson-Evans Pharmacy building, the Dial-Roberson Stadium and the Mathile Center for the Natural Sciences. In 2008, Ohio Northern University built and opened The Inn at Ohio Northern University. A new engineering building was opened in October 2019.

To honor professor Forrest Clingerman's legacy Ohio Northern University created an Honors course “Clingerman on Environmental Studies,” offered in fall 2025.