With minorities in America increasing so fast that they are expected to account for more than 50% of the country’s population sometime in the next 50 years, a new report being released today shows that immigrants are assimilating faster than those who came in the last big wave a century ago — especially immigrants living in New York City.

The Manhattan Institute report, which examined the cultural, political, and civic assimilation of immigrants during the past century, found that, against expectations, immigrant assimilation has remained steady even as the number of immigrants has doubled in the past two decades, and even though the new arrivals start out less assimilated than their earlier counterparts.

“The nation’s capacity to integrate new immigrants, by this measure, is as strong now as it has ever been,” the report says.

An associate professor of public policy at Duke University, Jacob Vigdor, is the author of the report, and the Manhattan Institute is hosting a conference today to discuss its findings. Two of the think tank’s most vocal immigration scholars, Tamar Jacoby and Steve Malanga, are not billed to appear on any of the panels.

The two scholars represent a major divide within the conservative community. Like the presumptive Republican presidential nominee, Senator McCain, Ms. Jacoby favors an overhaul of the immigration system that would provide a path to legalization for illegal immigrants. Mr. Malanga favors a more restrictive policy, representing a major contingent of conservatives who have made reducing illegal immigration a rallying cry for the right.

Rather than coming down on either side of the divide, the report appeared to offer fodder for both sides of the immigration debate going forward.

A perceived lack of desire to assimilate among the largest group of immigrants, Mexicans, has fueled arguments by groups opposed to illegal immigrants. But the report found that when it comes to cultural factors, including speaking English and marrying American-born citizens, Mexicans are assimilating at about the same rate as immigrants as a whole.

Mr. Vigdor also found that Mexicans have lagged behind others in economic and civic assimilation. He argued that part of the reason is that many come here illegally, blocking them from taking such major steps toward assimilation as becoming naturalized citizens and taking on high-paying jobs.

Mr. Vigdor suggested that allowing illegal immigrants to legalize could help propel the rate of Mexican assimilation. Then he added a caveat.

“The big question is by how much,” he said, adding that the proximity of Mexico to America and the economic motivations of most Mexican immigrants mean they may see becoming a citizen here and embracing other measures of assimilation as less of a priority.

Canadian immigrants, who are nearly identical to native-born Americans when it comes to culture, also lag when it comes to civic assimilation, the report found.

By contrast, the report found that Cubans, Egyptians, and immigrants from countries where the American military has been stationed, including Vietnam, have higher rates of civic assimilation.

Combining all three of the assimilation categories, the report found that the least assimilated immigrants are from Nepal, Cameroon, Guatemala, India, Mexico, and Honduras. The most assimilated are from Czechoslovakia, Panama, England, Hungary, Italy, and Scotland.

The executive director of the New York Immigration Coalition, Chung-Wha Hong, saw the report as generally positive for groups fighting for a more expansive immigration policy — and was especially thrilled that it had been produced by a conservative organization.

“I hope that this study will be used to promote public policy that help immigrants become citizens,” she said.

New York City was one of the best places for immigrants to land if they wanted to assimilate quickly, the report showed.

Mr. Vigdor suggested that the city may offer more opportunities for upward mobility, but also said the city’s high-end industries, such as finance and entertainment, may attract immigrants who are more assimilated on arrival.