Few commuters are familiar with Rush hour at Delta Upsilon.

The door of the frat house stands open on a cool, fall night and the plaster-cracking report of a Lynyrd Skynyrd record booms from the basement. Latecomers stream up the steps, hand over their ID cards and tumble downstairs, worming through the densely packed crowd in hope of gaining the tap, where Ziggy is dispensing Miller Lite for free.

September is the rushing season at the University of Maryland. It unfolds night after night in the party rooms of fraternity and sorority houses, a month-long round of draft beer, loud music, shouted introductions, sudsy handshakes and libidinous eye contact. All of it leads up to the sober decision of whom to induct into the fellowship of "Greek life."

But there is a new age dawning on Fraternity Row, and in the dormitories and bars of the sprawling university.

For the first time since 1974, almost half of the freshmen at the College Park campus -- those whose 18th birthdays fell after last July 1 -- are barred from drinking, under the state's new liquor laws. In three years, drinking will be illegal for nearly three-quarters of the undergraduate population.

In the environs of College Park, profound changes are anticipated. Already, the famous 100-keg parties at "LaPlata Beach" are gone and it is hard to find anyone underage in the famous Rendez-Vous bar. University officials say that it is too soon to tell how well the students will abide by the law, or what psychological effects it will have. But anyone who has suffered through a mixer may wonder: Will the young men and women at Maryland ever be able to speak to each other again? Will they be equal to the challenge, as described by one university graduate, of making a fool of yourself without an excuse?

While it is widely known that this gets easier to do after graduation, especially if one develops some stature in the world, the phasing-in of Maryland's new liquor law has prompted a lot of self-examination among student leaders.

Sororities never have served alcohol at rush parties at Maryland, but many fraternity rush parties depended upon it the way cars depend on gasoline. Some frats are experimenting with "dry rushes." The Intra-Fraternity Council, an umbrella organization with 25 member fraternities, has canceled its "Two O'clock Clubs," where people gathered on Thursdays to hoist a few at 2 a.m., and this semester is the last for GIGF, or "Gee, I'm Glad It's Friday," parties.

"What we're learning nowadays," says Danny Macey, social chairman of the IFC, "is how to have rush parties without alcohol. We've contacted alumni during Rush and said, 'How did you do it back then' " -- meaning the dim past, when the youngest age for legal drinking was 21.

For the time being, the brothers of Delta Upsilon have taken the law in stride, obligating themselves to strictly screening the freshmen who drop in to meet prospective brothers. As last Wednesday night's rush party in the Party Room developed, it was not long before the topic of liquor laws was brushed aside in favor of a discussion of Susie, and Allison, and a duo with blond hair whose names nobody knew.

The party room in the basement of the house is the center of life at Delta Upsilon, an open fraternity whose 36 brothers who do not haze pledges or have secret mottos or cabalistic ceremonies. The ceiling is low, the linoleum floor is sticky, but it's the best-kept room in the house. There is a bulletin board with DU news, lighted beer signs on the wall, a brick-and-wood bar, and two beer taps that pipe into kegs.

Somewhere in the hubbub of the party was Quin, who had lately been scaling small trees and shaking squirrels out of the branches in hope that Slade, a former U.S. Army Ranger, could have something to put on a skewer to ward off trespassers crossing the frat yard. Pudge and Snake reclined against the bar. Bob Sar and Allison Lambert were celebrating a year of dating. Backed against the door labeled Men's Toilet, John W. Smith the Third, as he introduced himself, lingered with a glass of Coke. He is a former frat member and a proud scholar of DU history and trivia who, at 32, still comes to Rush parties. The new drinking law is a boon, he said, because it will "cut down on wear and tear on the house."

Then there was Heidi Griebel, huddled in one of the few all-women circles. She touched briefly on the fate of her friend who was born July 4, 1964, three days after the date when the law went into effect, creating two classes of freshman: those who are of age, and those who need fake identification cards.

"She almost killed herself," Heidi said. "But she got a fake ID. She goes to James Madison. She told the registrar she was her older sister."

The atmosphere at the DU rush party was aboil with conviviality. No wallflowers were left to wither. No fiercely indifferent types were given the chance to affect airs of condescension. Rush chairman Anthony Philip, and the eminently political president, Brion Talley, were bent on making strangers feel at home.

Even a well-known outcast mounting a long-shot bid for a place in any of half a dozen fraternities, a young man ill-advisedly given to encircling girls with his arms and saying, "Hey, how would you like to get lucky?" -- even he latched on to somebody, at least for a few minutes.