Abstract: This study evaluates the use of the crosswalk between the PTSD Checklist-Civilian (PCL-C) and PTSD Checklist for DSM-5 (PCL-5) designed by Moshier et al. (2019) in a sample of service members and veterans (SM/V; N = 298) who had sustained a traumatic brain injury (TBI) and were receiving inpatient rehabilitation. The PCL-C and PCL-5 were completed at the same time. Predicted PCL-5 scores for the sample were obtained according to the crosswalk developed by Moshier et al. We used three measures of agreement: intraclass correlation coefficient (ICC), mean difference between predicted and observed scores, and Cohen's κ to determine the performance of the crosswalk in this sample. Subgroups relevant to those who have sustained a TBI, such as TBI severity, were also examined. There was strong agreement between the predicted and observed PCL-5 scores (ICC = .95). The overall mean difference between predicted and observed PCL-5 scores was 0.07 and not statistically significant (SD = 8.29, p = .89). Significant mean differences between predicted and observed PCL-5 scores calculated between subgroups were seen in Black participants (MD = -4.09, SD = 8.41, p = .01) and those in the Year 5 follow-up group (MD = 1.77, SD = 7.14, p = .03). Cohen's κ across subgroups had a mean of κ = 0.76 (.57-1.0), suggesting that there was moderate to almost perfect diagnostic agreement. Our results suggest the crosswalk created by Moshier et al. can be applied to SM/V who have suffered a TBI.