<p dir="ltr">Loneliness is a perceived discrepancy between desired and experienced social relationships, which may arise from perceived lack of intimate attachment to another person (e.g., friend) or lack of involvement in larger networks (e.g., peer groups). The current study examined and compared how different aspects of friendship and peer group involvement predicted loneliness of Indonesian adolescents. Participants were 754 twelfth-grade Indonesian students (413 girls, mean age = 16.5 years). Loneliness was self-reported. Reciprocated friendships were calculated from within-grade nominations and friendship quality was obtained from ratings pertaining to each nominated friend. Peer groups were generated from Social Cognitive Mapping (SCM) and status indices were calculated from SCM and peer nominations. A concurrent SEM model was tested where quantity and self- and friend-perceived quality of friendship, group membership (i.e., within-group centrality), and status of the group in the larger network (i.e., group centrality status and group popularity status) predicted loneliness. All predictors had unique negative effects on loneliness with generally similar effect sizes except for friend-perceived friendship quality. An interaction between within-group centrality and group popularity status was found for boys. The results revealed that quantity and quality of friendship as well as position in the peer group and the status of the peer group were associated with loneliness. Being central in a group may be more important for those in low-status groups than high-status groups. Group-related indices were comparable to friendship indices as predictors of loneliness, which may be shaped by Indonesian culture where group involvement is valued more than intimate friendships.</p>