What university did Michael Phelps attend?

Michael Phelps attended the University of Michigan. He moved to Ann Arbor in 2004 to train with his longtime coach, Bob Bowman, who joined Michigan's swimming program. Phelps enrolled in classes and trained with the Wolverines, although his status was unusual because he was already a professional swimmer with major endorsement agreements.

He did not compete for Michigan in official NCAA meets. At the time, NCAA rules restricted athletes who had professional endorsement arrangements, and Phelps's Speedo sponsorship made him ineligible for collegiate competition. He nevertheless trained at the university and became an important figure around its celebrated swimming program.

Phelps left Michigan without completing a degree, returning to Baltimore after Bowman departed for Arizona State in 2005. The university is therefore the accepted answer, even though “attended” does not mean he graduated or swam as an NCAA athlete. His connection to Michigan is also closely tied to Bowman, who coached him through much of his record-setting career.