According to the NATO (North Atlantic Treaty Organization) report, there are about 4,000 Muslims in Luxembourg. Up until the 1970s, the Muslim population was quite small. In the mid-1970s, the Muslim population counted only 300 people, going up to over 3,000 by the mid-1990s. Since then, the population has doubled due to asylum-seekers from former Yugoslavia, mostly Bosniaks. These asylum-seekers were never expected to stay more than a few years.
Before the 1960s, Muslims were relatively unheard of in Luxembourg, but as with other surrounding countries, they arrived and gradually the religion spread throughout the country. Today there are currently six mosques in Luxembourg: Mamer (which is also home to the Islamic cultural centre), Esch-sur-Alzette, Wiltz, Diekirch and Luxembourg City and it is estimated that about 10.000 to 12.000 Muslims reside in the Grand-Duchy. This means that Islam is now the second religion in Luxembourg, after Catholicism. However, this ranking is just an estimate, and is not corroborated. Further, it is unsure if all of these Muslims are citizens or not.