The main objective of the TRACK-TBI Epileptogenesis Project (TRACK-TBI EPI) is to determine how post-traumatic epilepsy (PTE) contributes to the negative neurological and psychological outcomes of individuals who experienced a traumatic brain injury (TBI), compared to subjects with comparable TBI without PTE. The study extends the follow-up of subjects from the TRACK-TBI and Spreading Depolarizations II studies to capture a larger subset of individuals who will develop PTE. With data collected via a combination of follow up phone screening and in-person visits, the primary study endpoint will assess the relationship between TBI severity and epileptogenesis.