This study examined children's peer information processing as an explanatory mechanism underlying the association between their insecure representations of interparental and parent-child relationships and school adjustment in a sample of 210 first graders. Consistent with emotional security theory (P. T. Davies & E. M. Cummings, 1994), results indicated that children's insecure representations of the interparental relationship were indirectly related to their academic functioning through association with their negative information processing of stressful peer events. Insecure interparental relationships were specifically linked with negative peer information processing patterns that, in turn, predicted increases in child maladjustment over a 1-year period. These pathways remained robust after taking into account the roles of representations of parent-child relationships, trait measures of child negative affect, and socioeconomic characteristics as predictors in the analyses. (Contains 1 table and 1 figure.)