Dartmouth College is banning hard alcohol from its campus and putting its notoriously rowdy fraternities on notice that they need to reform or disband, in the latest move by an elite school to crack down on a party culture that has been closely tied to sexual assault.

Dartmouth President Philip J. Hanlon on Thursday delivered a speech to faculty and students in which he laid out his plan to deal with a rising tide of complaints that have tarnished the reputation of the New Hampshire school, which has 4,289 undergraduates and...