Background: Dysarthria, aphasia and executive processes have been examined for their role in producing impaired communicative competence post traumatic brain injury (TBI). Less understood is the role of emotional dysregulation, that is, apathy and disinhibition, and social cognition, that is, reading and interpreting social cues. Methods & Procedures: In this study, we examined 49 adults with moderate to severe TBI and 18 neurologically healthy adults. We hypothesised that apathy and disinhibition would predict communication outcomes as would social cognition. We also predicted that apathy and disinhibition would influence social cognition. Communication outcomes were measured by the La Trobe Communication Questionnaire (LCQ) and the Social Skills Questionnaire-TBI (SSQ-TBI). Apathy and disinhibition were measured by the Frontal Systems Behavior Scale (FrSBe). We measured four aspects of social cognition: emotion perception and theory of mind using The Awareness of Social Inference Test (TASIT) and the Complex Audio-Visual Evaluation of Affect Test (CAVEAT), empathy using the Questionnaire of Cognitive and Affective Empathy (QCAE) and the Balanced Emotional Empathy Scale (BEES), and alexithymia using the Toronto Alexithymia Scale (TAS-20) and the Bermond-Vorst Alexithymia Questionnaire. Outcomes & Results: Consistent with predictions, the LCQ and SSQ-TBI were associated with disinhibition and the LCQ was also associated with apathy. The LCQ was associated with the full range of social cognition constructs although the SSQ-TBI was not. Finally, apathy and disinhibition predicted a number of social cognition measures. Conclusions and Implications: These results are discussed in relation to understanding the nature of communication disorders following TBI and how they are measured, as well as the interrelation between emotion dysregulation and social cognition.