Objective: Traumatic brain injury (TBI) sustained in childhood is associated with poor social outcomes. This study investigated the role of theory of mind (ToM) as a mediator of the relation between TBI and peer rejection/victimization and reciprocated friendships, as well as the moderating effect of parental nurturance on those relationships. Method: Participants were children of 8–13 years old (M = 10.45, SD = 1.47), including 13 with severe TBI, 39 with complicated mild/moderate TBI, and 32 children with orthopedic injuries. Data on peer rejection/victimization and friendship were collected in school classrooms using the Extended Class Play and friendship nominations. Parents rated parental nurturance using the Child-Rearing Practices Report. Finally, ToM was measured based on children’s average performance across three tasks measuring different aspects of ToM. Results: Severe TBI was associated with poorer ToM, greater peer rejection/victimization, and fewer reciprocated friendships. ToM mediated the relation between severe TBI and peer rejection/victimization (i.e., severe TBI predicted poorer ToM, which in turn predicted greater rejection/victimization). Parental nurturance significantly moderated this relation, such that the mediating effect of ToM was significant only at low and average levels of parental nurturance, for both severe and complicated mild/moderate TBI groups. Neither the mediating effect of ToM nor the moderating effect of parental nurturance was significant for reciprocated friendships. Conclusion: High parental nurturance may mitigate the negative effects of ToM deficits on risk of peer rejection/victimization among children with TBI. Interventions designed to increase parental nurturance or ToM may promote better social outcomes among children with TBI.