Youth involved with child protective services (CPS) are at elevated risk for engaging in self-harm. Participation in interventions or treatments that may reduce youths' self-harm behaviors often depends on the accurate reporting of their self-injurious behaviors. However, informants often disagree on the presence or severity of self-harm engagement, making the identification of youth in need of treatment more challenging. The current study aims to characterize discrepancies between youth and caregiver reports of children's self-harm among a sample of youth with a history of CPS involvement, and to identify factors (e.g., demographics, youth and caregiver psychological impairments, aspects of the caregiving environment) associated with these discrepancies. Participants (N = 258) were drawn from a large, nationally representative sample of youth under the age of 18 (mean age = 13.8) and their caregivers who were investigated by CPS. Multinomial logistic regressions were used to examine correlates of discrepancies in caregiver and youth reports of youth self-harm. Results indicated that 10% of caregiver-child dyads agreed on children's engagement in self-harm. In 33% of cases, only the child reported self-harm and in 57% of cases, only the caregiver reported youth self-harm. Being a biological caregiver, child female sex, higher levels of internalizing symptoms; higher post-traumatic stress disorder (PTSD) symptoms; and greater caregiver alcohol use was associated with a lower likelihood of caregivers reporting self-harm only. Older child age; lower externalizing symptoms; higher PTSD symptoms, and greater levels of caregiver emotional security and structure were linked to lower odds of children reporting self-harm only. These results underscore important factors to consider when assessing self-harm among youth involved with CPS and have potential implications for practice guidelines in this population.