Working in finance is straightforward enough in a Muslim country, where prayer breaks are typical and holidays like Eid al-Fitr, marking the end of Ramadan, are built into the calendar. But Muslim bankers in the United States have fewer resources. Many don’t have dedicated prayer rooms at work, and leaving the office to attend Friday prayers at a mosque can mean shuffling duties to a co-worker.

“We have a concept called law of necessity,” said Rushdi Siddiqui, global head of Islamic finance at Thomson Reuters. “You have to, at one level, abide by the laws of the land that you happen to reside in, whether it’s the formal laws or the unwritten laws.”

Perhaps the biggest impediment to greater participation by Muslims on Wall Street is that, by some readings, the Koran prohibits riba, or interest. Some Islamic scholars have interpreted the ban to be more inclusive of modern finance, and a subgenre of Sharia-compliant financial transactions, known as sukuk, has tried to bridge the gap.

Still, a vast majority of Wall Street deals are not Sharia-compliant. So observant Muslims at traditional banks are often forced to shift their boundaries. “What I was doing wasn’t 100 percent legitimate in terms of religious ruling,” Ms. Jukaku says of her work at Goldman. “But after a while, you stop feeling guilty, I guess.”

In 2006, three Muslim twenty-somethings formed a group to help fellow young professionals negotiate issues that arise. The organization, Muslim Urban Professionals, nicknamed “Muppies,” began as a Google group of around 50; members traded messages about job openings, notices of apartments for rent and announcements of group dinners. It has expanded to about 1,000 members globally, roughly half of whom work in finance, according to Mr. Iqbal, the hedge fund trader, who is now a national administrator of the group.

As the Muppies’ ranks have grown, more intimate questions have surfaced. Earlier this year, one member, who was about to start a job at a well-known consulting firm, e-mailed the group for advice. How, he wondered, could he succeed at his new job without compromising his Muslim values?

The consultant’s plea, under the subject line “Avoiding Alcohol and Opposite Gender Handshakes in the Corporate World,” received a vast range of responses. In regard to the alcohol issue, Muppies respondents divided into liberal, moderate and conservative camps — those who suggested that going to bars with colleagues was permissible, those who thought “drinking-focused events” were unadvisable but that dinners where alcohol was served were O.K., and those who insisted that places serving alcohol were to be avoided.