25% of the residents of Brussels are of Muslim origin, which makes Brussels one of the European cities with the largest Muslim presence, comparable to Birmingham in the UK. This according to a sociological study ('L'Iris et le Croissant' - the Iris and the Crescent) by UCL. The study was conducted by Sociologist Felice Dassetto, who has been researching Muslims, radicalization and intercultural ism for more than 30 years.
In total there are 250,000 to 300,000 Muslims in Brussels, about half the Muslim population of Belgium. 10-15% of the Muslims are practicing and active within religious associations.
Islam is also increasingly visible: there are more moques and minarets, more veiled owmen and more Muslim organizations.