To examine the association between social Internet use and real-world societal participation in survivors of moderate-severe traumatic brain injury.Prospective cross-sectional observational study.Ten Traumatic Brain Injury Model Systems Centers.A total of 331 participants in the Traumatic Brain Injury Model Systems, interviewed at any follow-up year between April 2014 and March 2015.Survey on Internet use, including social media and other online socialization; Participation Assessment with Recombined Tools-Objective with separate analyses of Productivity, Social Relations, Out and About subscales; covariates included demographics, injury variables, and functional and emotional status at follow-up.Participants were classified as social Internet users (N = 232) or nonusers (N = 99). Users had significantly higher Participation Assessment with Recombined Tools-Objective Social Relations scores than nonusers. A similar finding pertained to Out and About scores, with the between-group difference significantly greater for those with greater depressive symptoms severity. Users and nonusers did not differ significantly on Productivity subscale.The positive association between social Internet use and real-world social participation suggests that people with traumatic brain injury do not use social media as an alternative to real-world socialization. Rather, it is likely that similar barriers and facilitators affect both online and real-world social participation following traumatic brain injury. Emotional function should be considered as a moderating factor in further studies.