In this paper, we attempt to explain the differences between reading and math scores of migrants' children (8430 daughters and 8526 sons) in 17 OECD destination countries, coming from 45 origin countries or regions, using PISA 2009 data. In addition to the societal gender equality levels of the origin and destination countries (the gender empowerment measure), we use macro indicators of the origin countries' educational systems, economic development and religions. We find that migrant daughters from countries with higher gender equality levels obtain higher reading scores than comparable migrant sons do (but this is not the case for math scores). In addition, the higher the gender equality levels in the destination countries, the lower the reading and math scores of both male and female migrants' children in their destination countries. Further analyses suggest it is the difference between gender equality levels, rather than the levels themselves, that explains the educational performance of both female and male migrant pupils. Our results also show the low gender equality level in Islamic origin countries offers a possible explanation for the low educational performance of Islamic pupils, both male and female. Finally, migrants' daughters seem to perform slightly better educationally, compared with migrants' sons.