Half of all Muslim Americans say their leaders have not done enough to condemn Islamic extremism, according to a new poll showing widespread satisfaction with life in the United States, although many reported discrimination.

A decade after Sept. 11, 2001, the survey, conducted by the Pew Research Center for the People and the Press, shows that a majority of Muslims say the terrorist attacks made it more difficult to be a Muslim in the United States. Many said that they had been singled out by airport security officers and that people had acted suspicious of them or called them offensive names.

But half also said Americans had been friendly toward them, and three-quarters expressed faith that with hard work, they could get ahead.

“This is not an underclass,” said Andrew Kohut, president of the Pew center. “There’s a great deal of ‘We want to be Americans.’ They see opportunity here.”

The survey, to be released Tuesday, offers the most comprehensive look at Muslim American opinions since the last Pew poll, four years ago. The Muslim community is difficult to study. Two-thirds are immigrants from dozens of countries and cultures. And neither the Census Bureau nor immigration officials ask people for their religious affiliation.

Pew researchers conducted more than 1,000 telephone interviews in English, Arabic, Farsi and Urdu over three months this spring and summer, even as Rep. Peter T. King (R-N.Y.) was holding hearings about radical Islam in the United States and the Muslim community’s response.

The Pew study found that six in 10 U.S.-born Muslims faulted Islamic leaders for not speaking out against extremism, as did 43 percent of Muslim immigrants.

Officials with Muslim advocacy groups say that they have spoken out repeatedly against extremists but that the American public, including Muslims, often doesn’t hear about it.

“Our reach in terms of community awareness of our programs promoting moderation is not where we’d like it to be,” said Safaa Zarzour, secretary general of the Islamic Society of North America, the nation’s largest Muslim group.

Zarzour said that anti-Muslim sentiment in the United States is concentrated among a few individuals and groups. Most Muslims have warm relations with colleagues, neighbors and local public officials, he said.

“For a few years after 9/11, everybody got extremely scared,” he said. “Since then, religious and political leaders have acted more responsibly. Though the rhetoric has gone into high gear, the reality on the ground has been won, slowly but surely, by cooler heads and the better instincts of the American people.”

Pew researchers estimate there are 2.75 million Muslims in the country, up 400,000 from four years ago.

About 56 percent of those polled said they were satisfied with the direction in which the country is heading, compared with 23 percent of the general public. That may be a reflection of political views, the Pew study said. Most of those polled said they were Democrats who voted for President Obama.

A significant number of Americans remain wary of Muslims. Last year, in a Washington Post-ABC News poll, 31 percent of respondents said that mainstream Islam “encourages violence.”