The corpus callosum has been shown to be particularly vulnerable to the effects of traumatic brain injury (TBI) in childhood, and severe injury frequently results in a smaller corpus callosum post-injury. However, the long-term effects of TBI on the integrity of the callosum, as well as the potential functional significance of callosal injury are poorly understood. Some studies suggest the corpus callosum may be involved in social skills, which are often reduced following TBI. In this study, callosal size was investigated in 37 individuals 10 years post-childhood TBI, and its relationship with social competence was examined. The results indicate that individuals who sustain severe TBI in childhood display reduced callosal size 10 years post-injury. In addition, callosal size correlated significantly with social skills, suggesting that callosal atrophy may be related to poorer social skills after TBI. These findings highlight the persistence of callosal abnormalities, which may be a result of interrupted neural development after childhood TBI. The results further underscore the potential importance of the corpus callosum for social competence after TBI.