This longitudinal study examined the transactional relations between study habits and behavioral problems within and between children and the potential gender differences in the above relations during middle childhood in China. The participants were 260 children, drawn from 157 stable friendship dyads, who were initially in third and fourth grades (T1 Mage = 9.84 years). Parents completed internalizing and externalizing problem measures, children completed internalizing/externalizing problem and peer nomination measures and teacher reported study habits at two time points one year apart. The actor-partner analysis revealed that children’s internalizing problems negatively predicted their friends’ study habits one year later, and their externalizing problems negatively predicted their own and their friends’ study habits one year later. However, only girls’ study habits negatively and marginally predicted their friends’ externalizing problems. The results suggest that instructions integrating study habits and behavioral problems among peers may be an important avenue for enhancing children’s academic and social-emotion development in China, but these interventions should be distinct for boys and girls.