The literature suggests that religion may play an important role in the acculturation process of immigrants by contributing to the maintenance of the heritage culture and preventing identification with the mainstream. With few exceptions, studies on this topic have focused on religion as a whole by assessing specific aspects or dimensions (such as religious identification, beliefs, and practices) and creating a composite measure without analyzing the contribution of each dimension to the acculturation process. In this study, the relationships between specific religious dimensions and acculturation were assessed with a sample of 282 Muslim immigrants who were recruited in the northern part of Italy. Two regression models show that religious identification drives the maintenance of Muslim culture but is unrelated to the acculturation to Italian culture, whereas beliefs and practices do not contribute to heritage acculturation but are negatively associated to acculturation to the host culture.