The boys look sharp in white tuxedos. Their dates are lovely, if a bit stiff in formal gowns, corsages, and roses bought from a strolling vendor. The foursome from Waldorf, Md., knows that the only place to have dinner on prom night is in Georgetown -- and they all go off to order lobster with butter saude ($15.50).

By 10 p.m. a ribbon of cars stretches down M Street, all the way to the Key Bridge. Even foot traffic slows to a crawl. A Senate aide and his wife, in for a rare dinner without the kids, pause in front of the Riggs Bank building to watch Reginald Conyers play his euphonium, a scaled-down tuba. A senior at the Duke Ellington School of the Arts, Conyers earns $40 a week from the tips that are thrown into his instrument case. Across the street, two Bethesda high school girls play a Mozart concerto on their flutes to help finance a band trip to London.

Inside Nathan's, a corner tavern with an older crowd, Vincent J. Squillace, a lobbyist for the Ohio Homebuilders Association, is holding court with fellow conventioneers. The "great seal of the great state of Ohio" is pinned on his lapel.

Up Wisconsin Avenue, an Army general wearing a black cutaway coat with gold epaulets and chestful of ribbons heads for a nightcap with his date from a Navy nurse ball. A Unification church member sells roses at the busy intersection.

On the opposite corner, two crewcut young men from a Clinton, Md., Baptist church proselyte pedistrians who are more interested in bacchanalia than the Bible. Led by the Lord to Wisconsin and M, they shout, "Oh, generation of vipers, repent."

But at midnight, almost 400 young people are in the packed bar at Annie Oakley's. A rock video display of the New Wave group Devo is interpersed on the screen with a French fry crashing into a doughnut.

The evangelists scream on the sidewalk, but the sinners pay their cover charge, and keep on marching into the bar.