Previous research suggests that reduced self-awareness is common following traumatic brain injury (TBI). However, few studies have examined the magnitude of this problem in a sample representative of hospitalized individuals. In this longitudinal study, individuals with complicated mild to severe TBIs and their significant others (SO) were evaluated at 1 and 12 months postinjury on the Sickness Impact Profile. Awareness was measured by comparing the level of injury-related problems reported by a person with TBI and their SO. Overall, individuals with TBI did not report fewer difficulties than their SO. In contrast, they frequently reported more injury-related difficulties than their SO. As there is no commonly or universally accepted definition for differential awareness, the magnitude of underreporting and over-reporting problems is presented using four different cutoff scores. A minimum discrepancy is proposed for defining awareness difficulties that is based on the standard error of measurement of the test-retest difference of the measure. Reduced self-awareness was inconsistent across both time and functional domains. These results suggest that reduced self-awareness is not the norm at 1 or 12 months postinjury and highlight the need for a more standardized approach to the measurement and classification of self-awareness.