Last time, it was a published allegation of rape. This time, it is an indictment on charges of kidnaping, assault and attempting to extort money from his wife's alleged lover--charges to which he has pleaded not guilty.

Mayor Vincent A. Cianci Jr. again is getting the kind of national attention that makes many in this scrappy working-class city of 160,000 cringe with embarrassment.

For a Republican-independent mayor in a heavily Democratic town, such accusations might spell political disaster. But "Buddy" Cianci--a colorful and controversial three-term mayor with a staunchly loyal following in the Italian-American community--is still flying high, pursuing development funds in New York City and appearing on television interview shows to extoll the virtues of his city, and its mayor.

In a town where ethnic politics plays a large role, the Cianci indictment and the lurid nature of the current allegations have polarized an already divided political establishment--especially among his Italian-American supporters, who make up about 40 percent of the electorate.

Cianci, the city's first Italian mayor and the first Republican one here in 34 years, once was the GOP golden boy of Rhode Island. Nine years ago, running as a reform candidate, he toppled an Irish-dominated Democratic machine that had reigned unchallenged for decades, churning out patronage jobs and city contracts for its cronies.

Under Cianci's tenure, Providence has struggled--sometimes successfully--to shed its image as a dirty northeastern industrial town still staggered by the departure of the textile mills. Cianci has promoted a "partnership" with the private sector, and he points proudly to more than $200 million in new office and commercial construction during his tenure.

Even Cianci's critics acknowledge that many of the city's neighborhoods have been revitalized, often with city grants. In his early years as mayor Cianci was an energetic populist, showing up at so many community meetings, ethnic activities and block clubs that his technique prompted the joke that Buddy Cianci would attend the opening of an envelope.

But the city has had its problems under his tenure. It has flirted with bankruptcy, experienced a small taxpayers' revolt when he proposed a 20 percent property tax increase, and in 1981 had a 16-day municipal strike, during which police rode with shotguns on city garbage trucks.

Cianci scored his biggest coup last November. Running as an independent, he beat Democratic and Republican opponents to win his third term and become the first independent mayor here in a century.

But his career has been a political and personal roller coaster, with his political enemies in the Democratic establishment eager to capitalize on his foibles and topple his machine.

Now his antagonists on the Providence City Council are calling for his resignation, contending, among other things, that he will be too preoccupied to run the city while facing six felony charges bearing penalties of up to 71 years in prison and $10,500 in fines.

"The people who are anti-Cianci believe what they have always believed, that he is not a person fit for public office because of serious flaws in his personality," said Nicholas W. Easton, a Democratic council member. "He has a bad temper, but this is beyond that. He considers himself above the law."

Cianci, in a lengthy interview in City Hall, asserted his innocence and characterized his indictment as stemming from "purely a domestic matter" that does not impair his ability to govern.

"I was hoping to go through an amicable divorce, and complications resulted in an altercation . . . . I am a human being. I sweat. I feel. I cry. I laugh. I get angry," he said. "I am still going to run my city."

This is not his first trouble. On the wall outside Cianci's office--near the photograph of him with President Ford when the young mayor delivered Ford's seconding speech at the 1976 GOP convention--Cianci has hung a framed copy of a letter and a check.

It is the letter of apology and the $8,500 check he received from New Times magazine in connection with its July, 1978, cover story that explored charges that he raped a young woman in 1966 when he was a law student at Marquette University in Wisconsin.

The article in the now-defunct magazine reported that the alleged rape victim, a 20-year-old answering service operator, complained to police, but later dropped the charges after Cianci, then 25, paid her $3,000.

Cianci, who was never arrested or charged, filed a $72 million libel suit against the magazine, but his suit was dismissed. He appealed the decision, and the case eventually was settled with the letter and payment.

In the current case, the mayor stands accused of kidnaping, assaulting and threatening Raymond DeLeo, a wealthy Bristol, R.I., building contractor who was prominent in Republican circles and was formerly a close friend of Cianci. The mayor alleges that DeLeo was having an affair with Sheila Bentley Cianci, his wife of 10 years.

The Ciancis were granted a divorce March 15, and have been in the process of dividing property, including the palatial Cianci home in the city's fashionable east side.

On March 20, according to the indictment, Cianci and his police chauffeur, Patrolman James K. Hassett, who was also indicted, held DeLeo captive at Cianci's town house, where the assault is said to have occurred. The mayor, according to the indictment, assaulted DeLeo with a fireplace log, an ashtray and a lighted cigarette.

Cianci "maliciously" threatened to "put a bullet in his DeLeo's head" and destroy his business and reputation if he would not sign an affidavit dealing with the alleged affair, the indictment said. Both DeLeo and Sheila Cianci have declined comment on the alleged incident.

Cianci, an aggressive and energetic campaigner, has reacted as if it were another campaign, even joking about his troubles on the banquet circuit--telling listeners that the television networks want him to star in a new soap opera called "Providence."