Pretrauma internalizing and externalizing behaviors have been found to predict posttraumatic stress disorder (PTSD) symptoms (PTSS) in children following injury. However, child in-hospital self-report of pretrauma symptoms may be impacted by their injury and associated medical care (e.g., sedation/pain medications). Parental report of child pretrauma risk factors may be easier to capture; however, mothers and fathers differ in the extent to which they report, and agree on, internalizing versus externalizing behaviors in their child. The present study examined the differential utility of maternal versus paternal ratings of child preinjury internalizing, externalizing, and prosocial behaviors in predicting child PTSS 3- and 6-months postinjury. Eighty-four children were recruited from an emergency department after emergency medical services transport following injury, along with their parent(s). Dyadic (one parent and a child) analyses revealed that maternal reports of internalizing behaviors were significantly associated with child PTSS 3 months, F(5, 64) = 9.48, p< .001; ß = .44, p = .01, and 6 months, F(5, 48) = 5.57, p< .001; ß = .42, p = .03, postinjury. Paternal reports were not associated with child PTSS at either time point. In a subsample of triads (mother–father–child), mothers’ and fathers’ reports were only moderately correlated (rs = .30–.53), and neither maternal nor paternal ratings individually predicted child PTSS when both parents’ reports were included in the model. Exploratory analyses revealed that family conflict and maternal initial PTSS moderated the relationship between maternal ratings of internalizing behaviors and child 3-month PTSS. Results suggest that maternal reports of child preinjury internalizing behaviors should be considered as predictors of later child PTSS development. (PsycInfo Database Record (c) 2023 APA, all rights reserved)