Forty percent of 18- to 22-year-olds gambled monthly in 2007, according to the Annenberg Public Policy Center in Pennsylvania. That percentage actually represents a decline from 2006, thanks in part to a federal law that curtailed Internet gambling. Still, last year, about 5 percent gambled weekly and had problems such as spending more money than they planned.
The numbers could rise again as people find ways around restrictions to gambling online, experts say. Historically, new waves of gambling have met societal pushback, but "the pushback never took [participation] back to where it was prewave," says Mr. McClellan, editor of "Gambling on Campus," a collection of articles.
McClellan has seen the "devastating" consequences firsthand. "I had a student who came to me for protection because others were threatening him around money he owed," he says. Others stole from roommates, student groups, and even academic departments.
Shannon Shorr remembers seeing e-mails about the dangers of gambling as a freshman at the University of Alabama, Birmingham, in 2003, but he wanted in on the poker boom. He started "$5 house games" with friends and quickly moved into Internet poker.