Truman State University (TSU or Truman) is a public liberal arts university in Kirksville, Missouri, United States. It had 3,664 enrolled students in the fall of 2024 pursuing degrees in 55 undergraduate and twelve graduate programs.

The university is named for U.S. President Harry Truman, who was a Missouri native. From 1972 until 1996, the school was known as Northeast Missouri State University.

Truman State University was founded in 1867 by Joseph Baldwin as the "North Missouri Normal School and Commercial College". Baldwin was a pioneer in education, and his school quickly gained official recognition in 1870 by the Missouri General Assembly, which designated it as the "First District Normal School", the first public teachers' college in Missouri.

The school served a district comprising 26 counties: including Adair, Audrain, Boone, Callaway, Chariton, Clark, Howard, Knox, Lewis, Lincoln, Linn, Marion, Macon, Monroe, Montgomery, Pike, Putnam, Ralls, Randolph, St. Charles, Schuyler, Scotland, Shelby, Sullivan, and Warren.

Purple and white were adopted as the school's official colors after Basil Brewer wrote a school song entitled "The Purple and the White." They have remained as the school colors since.

In 1919, the school was renamed "Northeast Missouri State Teachers College". For the next four decades, it was commonly called "Kirksville State".

In 1924, a fire destroyed old Baldwin Hall and the library. The lake that once filled the current quadrangle, or "The Quad" (a prominent feature in pre-1924 photographs), was pumped dry in a futile attempt to douse the fire. The Quad now serves as a popular gathering place where students study play games, hold events, such as small concerts and fairs, and meet with one another.

The school's mission broadened significantly over the years, and by the 1960s, it was no longer simply a teacher-training school. Reflecting this, it was renamed "Northeast Missouri State College" in 1968.