Tens of thousands converged on downtown Washington yesterday to demonstrate for a variety of causes, but it was the numbers and passion of busloads of Arab Americans and their supporters that dominated the streets.

Eager to make their presence felt and their voices heard in the nation's capital as never before, Arab and Muslim families marched and chanted for an end to U.S. military aid to Israel, overwhelming the messages of those with other causes in a peaceful day of downtown rallies and marches.

Young men wore the Palestinian flag around their necks like a cape. Arabic was heard nearly as often as English, and cardboard signs held by women and children denounced Israeli Prime Minister Ariel Sharon and President Bush. Protesters rallying against corporate wrongs and the global economy found themselves tweaking Vietnam War-era chants to the Palestinian cause, shouting, "One, two, three, four: We don't want no Mideast war!"

"The message here is we must support the Palestinian people against a military occupation and an apartheid state," said Randa Jamal, a graduate student at New York's Columbia University who joined thousands at a pro-Palestinian rally near the White House. She said her cousins were killed in Ramallah, in the West Bank, and her 16-year-old sister has been unable to attend school because of the Israeli occupation. "What they are going through," she said, "is crimes against humanity."

Palestinian rights was the theme of two of four permitted marches that merged on Pennsylvania Avenue NW in a loud and colorful procession to the Capitol. The host of other issues -- anti-corporate globalization, antiwar and anti-U.S. policies in several areas -- were boiled down to an essence visible on banners, placards and T-shirts. Banners read: "Drop debt, not bombs" and "Peace treaty in Korea now." Bumper stickers on T-shirts declared: "No blank check for endless war" and "We are all Palestinian."

It was possible to stand on the Washington Monument grounds and hear simultaneous speeches from three rallies nearby -- antiwar demonstrators, counter-demonstrators and pro-Palestinian activists -- in a mind-boggling surround-sound mix. Protesters came from the Anti-War Committee in Minneapolis, Middlebury College in Vermont and the D.C. chapter of the International Socialist Organization. There were teenage anti-capitalists with black bandannas over their faces marching alongside Muslim mothers wrapped in traditional headdress and pushing baby strollers.

Other demonstrations are planned today and tomorrow near the Washington Monument grounds and outside the Washington Hilton, the site of a pro-Israel lobbying group's annual conference.

District police said the crowds were larger than they had anticipated and put the number at about 75,000. Metro transit officials said ridership increased significantly yesterday, but estimates would not be available until today. Organizers of the Palestinian-rights rally at the Ellipse said the gathering was the largest demonstration for Palestine in U.S. history.

"We are here because we want to do something, to send a message," said Amal K. David, a Palestinian American who made a 12-hour trip in a 21-bus caravan from the Detroit area to join the rally organized by International Answer, an antiwar, anti-racism coalition that shifted the theme of its protest as violence in the Middle East escalated. In tears, David spoke of the destruction that U.S.-financed Israeli weapons and tanks have done to Palestinians, saying: "My beloved country is financing such death and destruction. I am so ashamed."

Many pro-Palestinian marchers said they learned of the march through their mosques. "All over the U.S., everybody got the word," said Issam Khalil of the Bronx, who traveled in a fleet of 50 buses from New York.

Several downtown blocks away, thousands of other pro-Palestinian activists took to the streets for another march to free Palestine. The group was made up mostly of Arab Americans with relatives in the occupied territories and U.S. Jews opposed to the occupation.

"The Palestinians here in the crowd look at us mistrustfully at first," said Rabbi Yisroel Weiss, 45, of New York. "But then they speak a few words with us, and they show us respect and friendship." Weiss traveled to Washington with several dozen Orthodox rabbis to join the march, which left the Washington Hilton, joined anti-globalization demonstrators outside the Foggy Bottom headquarters of the World Bank and International Monetary Fund and continued on the Capitol. He said his group favored dismantling Israel and returning it to the Palestinians.

Buses carried Jewish supporters from Boston, Chicago, New York and Philadelphia, among other places.

Organizers at the march privately urged participants to strike swastikas from their posters, but few complied. It was a running debate among many participants, though several swastikas appeared on signs in reference to Sharon by day's end.

Walking down the sidewalk of Pennsylvania Avenue near the Justice Department as thousands filled the street, D.C. Police Chief Charles H. Ramsey praised the decorum of the demonstrations. "The organizers did an outstanding job," said Ramsey, baton in hand. "If it stays this way, it will be the best one we've ever had. . . . This is really what protest ought to be."

By about 4 p.m., no major clashes had broken out between police and protesters. The events were a stark contrast to Washington demonstrations in April 2000, when protests against the World Bank and IMF led to a virtual shutdown of the downtown area and sparked clashes between police and demonstrators that ended in mass arrests.

D.C. emergency officials said only two people were transported for medical treatment, though neither case was serious. Both were falls, one involving a police officer and the other involving a civilian.

Ramsey said that in his view, yesterday's demonstrations went smoothly because organizers worked closely with police. At least three field marshals from the pro-Palestinian side negotiated with Ramsey, then barked instructions into their speaker-phones.

Hani Ahmed, 16, of the District was one of them, and he was marching with a pro-Palestinian group that swelled the ranks of the anti-globalization forces across from the World Bank and the IMF. "That kid, he was only 16, and he was working so well with us. That was one of the things that made it work so well," Ramsey said. At one point, the parade got to Dupont Circle, and marchers wanted to go around the circle rather than through the tunnel, where their permit instructed them to go.

Tashim Sallah, 45, of Buffalo told Ramsey and Executive Assistant Police Chief Terrance W. Gainer that he was worried that people would suffocate in the tunnel. Gainer grabbed his hand and said, "We're going down with you. There's no danger."

The group followed Ramsey and Gainer into the tunnel and delighted in the cool shade and underground echo for their chants.

That cooperation was in marked contrast to the first day of demonstrations, when more than three dozen bike-riding protesters were arrested downtown during a Friday evening action at rush hour. All of the 41 people arrested were released, a D.C. Superior Court official said.

Yesterday, though, no incidents of that nature occurred. The only arrests came after most protesters had disbanded. Police arrested 24 adults and one juvenile who were found in a parking garage in the 1000 block of 13th Street NW. All were charged with unlawful entry, a misdemeanor, and police said they were scheduled to be arraigned tomorrow. Police said they collected backpacks, a riot helmet and a gas mask from the suspects, who were taken to the D.C. police academy in Southwest Washington.

Members of the group who were not detained said the demonstrators were not sleeping in the garage, as police first said, but had parked two cars there for the day's protests.

"They went back to the car to get food because they were tired," said Jacob, 23, who drove from Baltimore for the protests but would not give his last name. "We were going to leave to go home."

Earlier, the day was marked only by little dramas on street-corner stages among the tangle of protesters, tourists, police and counter-demonstrators clogging downtown on a humid, sticky afternoon. The atmosphere was mostly civil and occasionally comedic, with brief flashes of arguments or hostility.

About 1 p.m. at H and 16th streets NW, a small scuffle broke out between members of the New Black Panther Party and a man intent on disrupting them. A couple of dozen members of the party showed up at the anti-globalization rally wearing black masks and black military-style uniforms. They had swastikas and shouted anti-Jewish slogans. The scuffle amounted only to pushing and angry remarks before members of the crowd broke them up.

A short time later, the Patriots Rally for America -- a collection of counter-demonstrators that opposed the United We March antiwar protesters with whom they shared the Washington Monument grounds -- had heated up and was getting protection from 10 police officers on horseback and 13 more on foot.

At many points during the afternoon, D.C. police and federal authorities enveloped the marches and rallies with officers on foot and in cars, on horseback and on bicycles. But their presence was less dominating than in previous Washington demonstrations, and most officers were not outfitted in riot gear. More than a few were spotted at downtown intersections yawning or leaning on police gates.

"That's the way we like it," Ramsey said. "They ought to be low-key. People have a constitutional right to protest."

The effect of the pro-Palestinian demonstrators became evident when their smaller march joined anti-globalization forces outside the World Bank and IMF.

The emotion of the Mideast conflict appeared to overpower issues of economic fairness, and many of the signs and chants called for freedom for Palestinians and the end of U.S. sponsorship of Israel.

The Mobilization for Global Justice, which played a part in organizing the day's activities, acknowledged that the pro-Palestinian sentiment had overtaken its economic issues. "It seems more important to the safety of the world," said Mark Rickling, a Mobilization organizer. "But we're all united on the issues of oppression. I'm just floored by the amount of people here today."

By afternoon, the more militant forces of the pro-Palestinian movement dominated, with swastikas and anti-Sharon and anti-Bush slogans and banners.

Aside from handing out signs, organizers seemed to have taken care of nearly every need of protesters, in an ad-hoc way. One all-important telephone number -- 202-462-9627 -- was inked onto many arms; it's the number those arrested are to call.

Legal support was being provided at the number by a local law collective, the National Lawyers Guild, and D.C.-based Partnership for Civil Justice.

But yesterday, there were no confrontations or trouble during the marches. There was even day care, a service offered for many activist-parents by the Anti-Authoritarian Babysitters Club.

A gentle rain started about 2:30 p.m. as marchers walked along Pennsylvania toward the Capitol, but the sun broke through about 3:15.

By then, most marchers were at the east end of the Mall, and many had stopped to pray on the puddled ground.

Next came speeches and music and, as the light faded, the protesters began drifting away, with only 100 or so still on the Mall as a light rain began to fall at dusk.

Dave Sublett of Salem, Va., who is retired from the Air Force, rises from his wheelchair to salute, right, during playing of the national anthem at a pro-U.S. rally on the Washington Monument grounds.At Freedom Plaza downtown, pro-Palestinian demonstrators carry an "injured" 6-year-old girl from Philadelphia on a stretcher in protest of violence against Palestinians.At left, Lena Derani traveled to the demonstrations from Detroit, which sent a caravan of 21 buses on the 12-hour journey to the District.Below, the D.C.-based Committee in Solidarity With the Palestinian People holds a solidarity feeder march before joining International Monetary Fund and World Bank protesters. The coalition began its trek from the Washington Hilton, where the American Israel Public Affairs Committee, a pro-Israel lobbying group, begins its conference today.Above, multinational protesters join in support of the Palestinian cause during a morning rally on the Ellipse. Organizers said the event was the largest for Palestine held in the United States.D.C. Police Chief Charles H. Ramsey, right, and spokesman Sgt. Joe Gentile walk along Pennsylvania Avenue during the rallies. Ramsey praised organizers for their preparation.Tens of thousands turned out in Washington to march in support of Palestinians and against the policies of the International Monetary Fund and World Bank.Osher Zelig Estreicher, left, debates policy with Kamal Gafar, as do Rabbi Chaim Tzvi Freimann and Galal Elraida.