Despite findings that developmental timing of maltreatment is a critical factor in predicting subsequent outcomes, children's developmental stage is understudied in maltreatment research. Moreover, childhood maltreatment is associated with the development of maladaptive peer relationships and psychopathology, with social cognition identified as a process underlying this risk. The current study uses structural equation modeling to examine the impact of developmental timing of maltreatment (i.e., infancy through preschool versus elementary and middle-school years) on psychopathology via negative perceptions of peer relationships. Multi-informant methods were used to assess 680 socioeconomically disadvantaged children. Results did not support differential effects of early versus later maltreatment on children's internalizing symptomatology or disruptive behavior, but indicated that chronic maltreatment, relative to episodic maltreatment, has more severe consequences for children's internalizing symptomatology. Results further support the mediating role of children's perceptions of relationships in the effect of maltreatment on negative developmental outcomes.