We examined the joint role of constructive and destructive interparental conflict in predicting children's emotional insecurity and psychological problems. In Study 1, 250 early adolescents (M = 12.6 years) and their primary caregivers completed assessments of family and child functioning. In Study 2, 201 mothers and their 2-year-old children participated in a multimethod, longitudinal design with 3 annual measurement occasions. Findings from structural equation modeling in both studies revealed that children's emotional insecurity in the interparental relationship mediated associations between destructive interparental conflict and children's psychological problems even after including constructive conflict and family and child covariates as predictors. Conversely, emotional insecurity was not a mediator of associations between constructive interparental conflict and children's psychological problems when destructive interparental conflict was specified as a risk factor in the analyses. The results are consistent with the evolutionary reformulation of emotional security theory and the resulting primacy ascribed to destructive interparental conflict in accounting for individual differences in children's emotional insecurity and its pathogenic implications (Davies & Sturge-Apple, 2007). (Contains 2 tables and 3 figures.)