This 1-year longitudinal study examined the effects of academic performance and depression in friendships among elementary school children in China. Participants included 1122 children (44% boys) within 561 stable friendship dyads initially in fourth and fifth grades (initial M[subscript age] = 11 years). Data on academic performance, depression, and friendship were collected from multiple sources in the period of 2012 to 2014. Dyadic analysis using the actor-partner interdependence model showed that friends' academic performance significantly and positively predicted children's later academic performance, indicating same-domain effects, and significantly and negatively predicted children's later depression, indicating cross-domain effects, with a medium effect size ([epsilon][subscript 3] = 0.70) for the effects of academic performance. The results help understand the role of friendship in children's development in the Chinese context.