This study investigates the relationship between cognitive impairment, as measured by Orientation Group Monitoring System (OGMS) scores, and disability as measured by Functional Independence Measure (FIM) scores in a sample of 122 persons with traumatic brain injury admitted to an inpatient rehabilitation unit. The relationships between Aggregate OGMS and FIM Total, FIM Motor, and FIM Cognitive scores were significant (rho = .49, p < .001; .40, p < .001; and .64 p < .001 respectively). Lower cognition was related to greater disability; with this relationship stronger for FIM Cognitive versus FIM Motor scores. Consistent with prior research, time to rehabilitation was significantly related to FIM Total (rho = -.42 p < .001) at admission to rehabilitation, with shorter time to rehabilitation related to greater functional independence. Stepwise regression indicated that the Aggregate OGMS score contributed 24%, and time to rehabilitation 5% unique variance to FIM Total score. These results support previous findings of distinct cognitive and motor subscales of the FIM, and suggest the importance of cognitive impairment to both.