The current study examined the bidirectional associations between perceived social support from parents, teachers, and peers with students’ internalizing and externalizing behavior problems across lower secondary school. A total of 1,746 students (47.7% girls; M age = 13.76) in Finland completed questionnaires in Grade 7 and again in Grade 9. Based on a cross-lagged panel model, only peer support and internalizing problems showed a negative bidirectional association over time. Internalizing problems negatively predicted parental support, while parental support negatively predicted externalizing problems. Additionally, externalizing problems negatively predicted teacher support. The findings highlight the unique associations with different social support sources and show how a lack of social support may foster behavioral problems, yet the presence of behavior problems can also elicit reduced social support.