Quinnipiac University officials evacuated The Carl Hansen Student Center and Tator Hall at the Hamden campus on Wednesday due to a bomb threat.
The Regional Bomb Squad investigated reports of a pipe bomb but found no threat to the building.
It happened around 2 p.m., and the building was cleared and reopened by 4:30 p.m., according to school officials.
Classes at the Tator Hall were moved online for the rest of the day as a precaution.
The Carl Hansen Student Center is where the cafeteria is located, and the Tator Hall hosts academic classrooms.