“We think there is a bias against the Muslim institutions,” said Kevin Vodak, the lawyer for CAIR-Chicago. He noted that the board rejected the Irshad proposal without explanation, which is highly unusual, and that last fall the county took up an amendment to prohibit any new religious institutions in residential areas. “Most of the new proposals are from Muslims,” Mr. Vodak said.

For area Muslims, practicing their faith can require traveling to mosques outside their communities or gathering in residential homes to pray. Now after years of fundraising and preparation, several groups want to move ahead with plans for their own places of worship in DuPage County.