["Behavioral Sciences &the Law, EarlyView. ", "\nABSTRACT\nPrevious research on the mediating role of the quality of social relationships between material deprivation and adolescent health has predominantly utilized samples from mainstream populations to examine mental health outcomes, neglecting the critical need to explore behavioral health outcomes, such as substance use, particularly in socioeconomically disadvantaged adolescents. Using structural equation modeling with data from 1329 Taiwanese adolescents living in poverty and receiving social assistance, the study found that the quality of social relationships with family members, teachers, and peers significantly mediated the association between material deprivation and substance use. The family–adolescent relationship quality significantly mediated the association between material deprivation and psychological distress, while the quality of peer and teacher–student relationships did not. The mediating mechanisms of social relationships are similar across different age subgroups and sexes. This study informs practices addressing psychological distress and substance use issues via family and relational pathways.\n"]