TRAPPES, France — For the Muslims of Trappes, decades of praying in basements and cramped rooms in decrepit buildings will soon be over, once the finishing touches are applied to their new, hard-won mosque — a shiny domed structure with a minaret and wooden Moroccan doors.

It took sit-in protests in front of City Hall in Trappes, some 45 miles southwest of Paris, to get approval for the mosque in 2000.

With different customs, beliefs and often skin color, parts of France's large immigrant population have been shunted to the margins of French life.

Those tensions partly explain the eruption of rioting that has engulfed low-income suburbs and towns.

Trappes' new mosque, now open for prayers and soon to be open full-time, offers hope for many here that, with a proper venue allowing Muslims to worship in the open, youths may be less tempted to turn to religious radicalism.

"We wanted a respectable place of worship," city councilwoman Khadija Aram said of the new $2.7 million mosque. Aram is a secular Muslim of Algerian origin.

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cross the nation, many Muslims say they are still humiliated by the need to pray in cramped quarters in the basements of housing projects because of a lack of mosques.

Even in Paris, Muslims are forced to spill out onto the street, worshipping on trash-strewn pavements, at Friday prayers because some mosques are so small. France has some 5 million Muslims, the largest such community in western Europe.

The social unrest has forced the nation to confront immigrants' feelings of discrimination and France's shortcomings in integrating them.

Since colonial times, France's emphasis on integration has translated into a strong drive to assimilate cultures into a single French mold according to the nation's strong secular traditions.

In 2004, a law banning "ostentatious" religious symbols, and aimed at Islamic head scarves, went into effect — angering many Muslims.

Immigrants and French of immigrant origin — often Muslims from former colonies in North Africa — largely populate the low-income quarters ringing big cities.

In such conditions, Muslims "have no means to weigh in on decisions that could change their own situation," said Angelina Peralva, a sociologist who specializes in urban violence. "They are so consigned to their world that, collectively, they can't get out."