The effect of interparental conflict (IPC) on adolescents has captured the attention of researchers for the last decades, but the study of the effect of IPC on the emotional security of adolescents in residential care (RC) based on Emotional Security Theory (EST) is limited. In this study, we examined adolescents' emotional security and insecurity (preoccupation and disengagement) determined by dimensions of IPC. Participants were 917 Spanish adolescents (Meanage = 15.07 years, SD = 1.75), 51% girls and 49% boys, divided in two subsamples: 171 adolescents living in RC and 746 adolescents living with their families (F). We used the Children's Perception of Interparental Conflict Scale (CPIC) to explore interparental conflict dimensions, and the Security in the Family System Scale (SIFS) to analyze adolescents' emotional security in the family. Results showed that females perceived higher conflict and threat, and were more disengaged than males. Males self-blamed more and were more emotionally secure than females. Adolescents in RC perceived higher IPC, threat, and self-blame and were more insecure than adolescents F. Multigroup structural equation modeling comparing RC and F adolescents, and females and males showed similar causal negative relationships between conflict properties and security, and positive relationships between threat, disengagement and preoccupation. These results have implications for researchers and for practitioners when addressing family reunification for adolescents in RC or risks in community samples.