Abstract: Previous studies on social stratification and intergenerational mobility have mostly focused on the effects of parents on their children's socioeconomic status attainment, but less attention has been paid to the important role played by grandparents in the life chance of their grandchildren and its underlying mechanism. By analyzing a national survey sample data of junior high school students, this study examines the influence factors of living with grandparents and their effect on the academic performance of adolescents, and the intermediate mechanism. The study finds that:(1) Three-generation cohabitation occurs when there is a functional need for the nuclear family. Children with lower socioeconomic status, working mothers, or single parent families, are more likely to live with their grandparents; (2) Living with grandparents has significant positive effects on adolescents' academic performance after controlling other factors; (3) The effect of living with grandparents is moderated by the family's socioeconomic status and family structure, and students from lower-level or non-parent families benefit more from living with grandparents; (4) Living with grandparents to a certain extent benefits grandchildren's academic performance by enhancing family social capital investment. Households living with grandparents invest significantly more in the social capital for children than those who do not. The results of this study show that in modern society, family kinship network still plays a very important role in the status attainment and social mobility of individuals. Therefore, scholars should pay more attention to the important role of extended families in social stratification and mobility and its micro-mechanism.

Key words: grandparents, multi-generational living arrangement, adolescent's academic performance, family social capital