The battle to regain Georgetown on Halloween, planned and outlined in meetings over the last few months, will be waged tonight by police intent on ending the unruly celebration.

The strategy is to keep the crowds away. Streets will remain open to traffic, a critical component intended to discourage the block-party atmosphere of the past few years.

Police will be stationed at key entry points into Georgetown and they will be prepared to stop cars and people from entering if the crowds grow too large. The Fire Department will enforce maximum occupancy restrictions at bars, and police will arrest anyone drinking in public or carrying an open alcohol container.

Vehicles will not be allowed to park on Wisconsin Avenue NW between K and R streets or on M Street between 29th and 34th streets. The no-parking rules, already in place on weekend nights, provide one more traffic lane and eliminate what in the past has been a Halloween gridlock of revelers.

On Wisconsin Avenue, between K and P streets, police will seal side streets to all but residents and those who have "legitimate business." This is intended to limit traffic to the two main arteries, Wisconsin and M.

The unsanctioned Halloween celebration, which began in the early 1980s, drew 150,000 people in 1987. Since then, the crowds have declined steadily, due to a combination of bad weather and the fact that the feast has fallen on a weekday.

But after last year -- when three men were stabbed, one fatally, in a brawl -- business leaders, community activists and city officials decided the party had to end. The turnout of 60,000 people last year was still considered unmanageable by police. Emergency vehicles reported long delays in reaching the scene.

In September, city officials and Georgetown business and civic leaders met and, for the first time, outlined the plan that goes into effect tonight.

"We all agree that Halloween needs to be toned down," said Peter Armato, executive director of the 250-member Business and Professional Association of Georgetown. "It's near unanimous participation on this."

Contrary to popular perception, Armato and others said, most businesses do not profit from the crowds. Many of the revelers are underage and are not allowed to drink in bars, and the gridlock of past Halloweens has discouraged diners and others from the area.

Georgetown activists welcome the city's action on the celebration. "This is merely a matter of too many people in too small a place," said Ray Browne, a Georgetown activist running for the D.C. Council, who met repeatedly with city officials to get the streets closed.