Objective: To longitudinally investigate financial capacity (FC) following traumatic brain injury (TBI). Design: Longitudinal study comparing FC in cognitively healthy adults and persons with moderate to severe TBI at time of acute hospitalization (Time 1) and at 6 months postinjury (Time 2). Setting: Inpatient brain injury rehabilitation unit. Participants: Twenty healthy adult controls and 24 adult persons with moderate to severe TBI. Main Outcome Measures: Participants were administered the Financial Capacity Instrument (FCI-9), a standardized instrument that measures performance on 18 financial tasks, 9 domains, and 2 global scores. Between- and within-group differences were examined for each FCI-9 domain and global scores. Using control group referenced cut scores, participants with TBI were also assigned an impairment rating (intact, marginal, or impaired) on each domain and global score. Results: At Time 1, participants with TBI performed significantly below controls on the majority of financial variables tested. At Time 2, participants with TBI demonstrated within group improvement on both simple and complex financial domains, but continued to perform below adult controls on complex financial domains and both global scores. Group by time interactions were significant for four domains and both global scores. At Time 1, high percentages of participants with TBI were assigned either "marginal" or "impaired" ratings on the domains and global scores, with significant percentage increases of "intact" ratings at Time 2. Conclusions: Immediately following acute injury, persons with moderate to severe TBI show global impairment of FC. Findings indicate improvement of both simple and complex financial skills over a 6-month period, but continued impairment on more complex financial skills. Future studies should examine loss and recovery of FC following TBI over longer time periods and a wider range of injury severity. © 2012 American Psychological Association.