Residents of the tiny resort town of Dewey Beach, Del., voted in a vigorously contested election yesterday to ban drinking on the town's beaches during the summer months, ending a policy that has given the Atlantic coast municipality a reputation as a party town.

Election judge Alice Walsh said last night that leaseholders eligible to cast ballots in the town election voted 531 to 356 for the booze ban. Supporters of the ban have said they believed it would reduce what they call a troubling recent upsurge in disorder and rowdiness.

"We're going to see it return to a family, a quieter, beach," said outgoing Mayor John Farrow.

Town Police Commissioner P. Brooks Banta had said that he favored the public's right to drink and would have preferred to protect it by "eliminating . . . undesirables."

Even before the results were known yesterday, however, he said the law would be upheld, whatever the outcome of the balloting.

"Whatever goes down we will enforce it," he said. The number of officers rises from five in the off-season to 24 in the summer.

Dewey Beach has an off-season population of about 115 that can grow to 40,000 on holiday weekends during the summer months.