NEW ORLEANS — Douglas Barry spent Mardi Gras shouting warnings at the wildly costumed merrymakers on Bourbon Street as he carried a big sign reading, “Heed the Words of God.”

“We don’t really approve of Mardi Gras,” said Mr. Barry, a member of the Bible Believers, a Christian group that travels to large gatherings to preach. Around him were men dressed in pink baby-doll pajamas or leather loincloths, and women flashing glimpses of flesh for beads.

Mr. Barry took photographs yesterday as other members of his group preached to the revelers, who either ignored them or yelled back their own counterpoints.

“Not everyone welcomes our message,” Mr. Barry said. “But people never need to hear it more than today.”

Historically, Fat Tuesday was when people used up the fat in their larders before Ash Wednesday and the austerities of Lent. In Louisiana, it’s the last of 12 days of Carnival parades and parties, a celebration characterized by family-friendly parades uptown and in the suburbs — and by heavy drinking and lots of near-nudity in the French Quarter.

Not all the costumes were scandalous. Many had a political theme in honor of Super Tuesday — though Louisiana was not among the 24 states holding presidential primaries or caucuses.

Kim Disselliss, 49, simply taped a sign to her back showing Senator Clinton dressed as George Washington and reading, “Monica Lewinsky’s X-Boyfriend’s Wife for President. 2 for 1 Sale.”

Crowds that had begun staking out spots on the parade routes as early as Friday night spent the day collecting beads and other trinkets thrown from floats.

Crowd estimates were not expected until today, but the celebration appeared to have bounced back strongly since Hurricane Katrina flooded more than 80% of the city in 2005. Mardi Gras crowd estimates hovered around 1 million in the years before Katrina, and the crowd reached about 800,000 last year.

Clarinetist Pete Fountain, dressed in a tunic as one of King Arthur’s knights, looked frail but happy yesterday morning as he led 100 members of his Half-Fast Walking Club onto Uptown streets in what has become the city’s unofficial opening of Mardi Gras.

“Oh, I’m feeling fine. You always feel fine on Mardi Gras,” Mr. Fountain, 77, said. He’s had health problems since Hurricane Katrina, but still plays two days a week at a Gulf Coast casino.

While the walking club was on its way, floats of the Zulu parade headed for their starting point. Zulu, the black community’s oldest parade, was followed by the Rex parade, with businessman John Koerner III reigning as Rex, King of Carnival and Monarch of Merriment.

In Cajun country, costumed riders on horseback set out on their annual Courir du Mardi Gras, a town-to-town celebration. Hundreds of people registered for the Courir de Mardi Gras in Eunice, a bayou community 150 miles west of New Orleans.

Sporadic violence has marred the celebration. At least nine people had been wounded by gunshots, six of them on Saturday. Police said 1,100 officers, state troopers and National Guardsmen have been positioned along parade routes since the season began.

Still, most partygoers were undeterred. The smell of charcoal and sizzling meat accompanied the sounds of people urging float riders to “throw me something,” and band music played as cooks prepared everything from burgers to crawfish along the parade route.

“We had beer for breakfast, but we’re making it a side dish now,” David James said. “You have to pace yourself when you get here at dawn.”