The policy begins this fall and will be phased in over four years, The Washington Post reported Wednesday. All incoming freshmen will be housed in men- or women-only residence halls, with sophomores added next year.
University President John H. Garvey said studies show there is less casual sex and binge drinking in single-sex housing.
"We just thought it was a more wholesome environment," Garvey said. "A little separation is a healthy thing."
Only 11 of the university's 17 dorms are now coed. Unlike many secular schools, the university always housed men and women on separate floors with strict rules about after-hours mixing.
Bill Durdach, a recent graduate who once monitored a male-only floor, does not believe the change will make much difference in student behavior.
"College people are going to be drinking regardless of if there's a girl living above them or below them," he said.
U.S. colleges began creating coed dorms in the 1970s. The trend was driven by the need to find housing for large numbers of women.