Rural-to-urban migration within China is one of the important drivers of transformation in economic and social conditions in the twetny-first century. This study uses data from a new nationally based sample, the China Family Panel Studies (CFPS), to capture the multidimensionality of migration, household registration, and current residence and examines school pacing and verbal and math achievement among adolescents ages ten to fifteen. The study finds little evidence of significant migration effects after controlling for family structure, socioeconomic status, and county characteristics, except for one select group— urban “left-behind”—who are the most advantaged in both math and language achievement. Girls who are coresident with siblings demonstrate an advantage compared to boys who are coresident with siblings on language skill while it is singleton girls who demonstrate a disadvantage compared to singleton boys on math skills. Both girls and boys coresident with siblings perform lower overall than singleton boys on mathematics achievement. In modern China, male children in singleton families exhibit the gendered mathematics achievement test advantage that is well recognized in the international literature, whereas male children coresident with siblings more closely resemble girls.