As campus shootings continue to make headlines, student participation may increase, Healey said. At Princeton, 90 percent of first-year students are enrolled, compared with an overall rate of 64 percent for all undergraduates.
The school's application for admission now asks potential students to provide their cell phone numbers in case of emergency.
"These kids lived through Virginia Tech," he said, referring to the freshmen. "They were high school seniors about to head off to college."