This study investigates the longitudinal relationships among child maltreatment, emotion regulation, peer acceptance and rejection, and psychopathology. Data were collected from 421 children (215 maltreated and 206 nonmaltreated) aged 6-12 years from low-income families. Camp counselors evaluated emotion regulation and internalizing/externalizing symptoms, and peers nominated children for acceptance and rejection. Structural equation modeling revealed that experiencing neglect, physical, and sexual abuse, multiple maltreatment subtypes, and earlier onset were related to emotion dysregulation. Lower emotion regulation at Time 1 was associated with higher externalizing symptoms at Time 1, which contributed to later peer rejection at Time 2, leading to higher externalizing symptoms at Time 2. Conversely, higher emotion regulation at Time 1 predicted higher peer acceptance over time, which was related to lower internalizing symptoms, controlling for initial symptom levels. The findings highlight the role of emotion regulation as a risk or protective mechanism in the link between early child maltreatment and later psychopathology through its influence on peer relations.This study investigates the longitudinal relationships among child maltreatment, emotion regulation, peer acceptance and rejection, and psychopathology. Data were collected from 421 children (215 maltreated and 206 nonmaltreated) aged 6-12 years from low-income families. Camp counselors evaluated emotion regulation and internalizing/externalizing symptoms, and peers nominated children for acceptance and rejection. Structural equation modeling revealed that experiencing neglect, physical, and sexual abuse, multiple maltreatment subtypes, and earlier onset were related to emotion dysregulation. Lower emotion regulation at Time 1 was associated with higher externalizing symptoms at Time 1, which contributed to later peer rejection at Time 2, leading to higher externalizing symptoms at Time 2. Conversely, higher emotion regulation at Time 1 predicted higher peer acceptance over time, which was related to lower internalizing symptoms, controlling for initial symptom levels. The findings highlight the role of emotion regulation as a risk or protective mechanism in the link between early child maltreatment and later psychopathology through its influence on peer relations.