In this dissertation, I set out to describe religiosity and religious trends among the Dutch Muslim population, and to assess the influence of the social integration of Muslims in co-ethnic minority and majority social networks. Muslim immigrants in the Netherlands migrated from countries in which the vast majority of the population is Muslim (such as Turkey and Morocco), to a relatively secular context, in which Islam is truly a religion of immigrants. The second generation is currently growing up, and is caught between the religious world of their parents and the broader secular environment. In addition to being relatively secular, attitudes towards Muslims in the Netherlands have become quite negative in recent periods. Against this background, I asked what were the trends in religiosity of immigrants and their offspring and how these relate to their social integration. Contrary to expectations from a secularisation perspective, I did not find strong evidence of religious decline over time or generations. Rather, my analyses show relatively stable religious alignment of Turkish- and Moroccan-Dutch populations at a very high level over time. Being Muslim remains an important part of the social identities of many of the Turkish- and Moroccan-Dutch across both generations. Moreover, religious identification has clear behavioural implications so that most self-identified Muslims engage in some form of religious practice. Finally, religiosity is also consequential in terms of attitudes towards crucial life choices (such as partner choice) and towards religion in the public domain (such as the role of religion in politics). In line with the key role of embeddedness within the minority group in explaining high degrees of religious continuity, religion is successfully transmitted within immigrant families and further reinforced by co-ethnic friends, and to a lesser extent by the presence of co-ethnic neighbours. At the same time, I found that the more Dutch majority friends Muslims have, and the more they identify as ...