Amherst police said 68 people were arrested and four officers suffered minor injuries as they worked to disperse thousands of unruly students in several large crowds over the weekend.
Police in riot gear had to use pepper spray to disperse a crowd of students outside an off-campus apartment complex who were throwing beer cans and bottles at officers.
A university spokesman said students arrested would have details of their behaviour reviewed under the institution's code of conduct. Sanctions can include suspension or expulsion from the university.
Most of those arrested were charged with failing to disperse and disorderly conduct.
The "Blarney Blowout" is an annual event held in the run-up to St Patrick's Day on March 17 and has caused trouble for law enforcement agencies in the past.