The tear gas was used after fights broke out and officers were pelted with bottles and cans, but police say using it was a last resort.
Police say that 3,000 to 4,000 people had gathered a party late Saturday. Fifty-two people were arrested and 48 others were ticketed for various offenses.
Police say many of the troublemakers weren't Michigan State students, but say more charges could be coming after police review videotape.