This PhD dissertation discusses three important topics in labor economics. It consists of three chapters that inquire into the integration of migrants and their socioeconomic outcomes in the host country market by relying on an empirical framework combined with economic theory. The first chapter explores whether naturalization leads to faster occupational assimilation for immigrants in the labor market in Germany. In particular, the empirical analysis in this paper investigates whether immigrants become occupationally more mobile after naturalization and if this leads to better jobs in the labor market. Instrumental variable estimation is exploited to control for the time-invariant and -variant unobserved individual characteristics. In order to do so, changes in German immigration law in the 1990s is used as an instrument for naturalization. The results show that naturalization is not associated with an immediate increase in occupational mobility. Instead, the years following naturalization are associated with higher occupational mobility, which implies that immigrants use naturalization in the German labor market to pursue better occupation match and faster occupational assimilation. The second chapter exploits the September 11 as an exogenous event to explore whether September 11 decreased the exit rate from unemployment of immigrants from Muslim countries in the UK labor market. The empirical analysis exploits discrete time duration models. The results show that the exit rate from unemployment to paid employment decreases after the September 11 terrorist attacks for immigrants from Muslim countries compared to UK-born white population with similar socioeconomic characteristics. Moreover, a significant increase in the unemployment spell is found for the first generation immigrants from Muslim countries while no impact is found on second generation immigrants. The last chapter addresses issues related to religious identity which have been questioned more intensively in recent years. The first part of the empirical analysis answers the question about the extent to which religious identity is transmitted from one generation to the next by using longitudinal data from Germany. In addition, the empirical analysis investigates how socio-economic characteristics influence the transmission of religious traits across generations. Furthermore, the paper explores whether migration background plays a role in the transmission process. The results show that parents play an important role in the development of the religious identity of their children in Germany. The transmission or religious traits across generations varies according to the socio-economic characteristics of transmitter and religious groups. Finally, the empirical research shows that migration background is an important factor in the transmission process. The results reveal that vertical transmission is higher among immigrant families by using data from Indonesia and Turkey.