Children's peer beliefs have been shown to mediate the link between stress experienced within the peer group and later internalizing symptoms. This study extends this research by examining bidirectional associations between children's peer beliefs, friendlessness, and perceived friendship quality (i.e., receiving provision, negative treatment) and identifying indirect pathways to internalizing symptoms. Participants (N = 366; M[subscript age] = 9.34 years, SD = 0.07; 196 girls) reported on their peer beliefs, classroom friendships, friendship quality, and internalizing symptoms at 3 time points across 1 calendar year. Receiving provision from friends predicted less negative peer beliefs. Negative peer beliefs predicted less received provisions from friends and higher levels of negative treatment, and, in turn, negative treatment from friends predicted higher levels of internalizing symptoms. These findings provide novel insights into how perceptions of the peer group relate to dyad-level relationship processes, including the potential contribution of peer beliefs to children's peer adjustment.