The process of international migration has recently become increasingly complex and diverse in many countries. In attempts to understand the complicated conditions for international migration, two important branches of theory have emerged: the segmented assimilation theory and theories of transnationalism. The segmented assimilation theory has emphasized that the trajectories of assimilation depend on the characteristics of the immigrants and the social environments for receiving these immigrants (Portes et al., 2005). The impact of transnationalism on educational attainment among immigrant children must also be considered, because recent technological developments in communication and transportation have enabled migrants to move regularly across borders and maintain their ties with people in the sending community (Tsuda, 2003). However, transnational activities among immigrants have not been conducted outside the local settings of immigrant communities (Itzigsohn and Saucedo, 2002). To understand the conditions for immigrants and their offspring, two important immigration theories must therefore be considered. These theoretical arguments, although useful in understanding immigrants in different settings, have been premised mainly on the experience of immigrants in the US. For instance, the model of downward assimilation in the segmented assimilation theory rests on the unique history of race relations in the US (Boyd, 2002). Widespread poverty and a high incidence of crime have been observed in American inner-city ghettos. While some immigrants in Europe reside in more deprived areas, these places have not been as seriously deprived, in terms of their social problems, as their US counterparts (Thomson and Crul, 2007). Furthermore, the segmented assimilation theory appears to neglect the national context within which immigrant children are accepted (Portes and Rumbaut, 2001). In contrast, research on immigrant children in European countries has revealed that national variations in educational systems can explain differing patterns of integration among immigrant children (Thomson and Crul, 2007). However, little is known about the integration of immigrant children in Asian countries, several of which have recently accepted large numbers of immigrants from other countries (Tsuda, 2006). The research on the educational attainment of immigrant offspring in Japan may contribute to the further development of immigration studies because the national context for the reception of immigrants differs widely between Asian and European countries (Skrentny et al., 2007).