This study examined the psychometric properties of the posttraumatic stress disorder (PTSD) Checklist for Diagnostic and Statistical Manual of Mental Disorders-Fifth Edition (PCL-5; Weathers, Litz, et al., 2013b) in 2 independent samples of veterans receiving care at a Veterans Affairs Medical Center (N = 468). A subsample of these participants (n = 140) was used to define a valid diagnostic cutoff score for the instrument using the Clinician-Administered PTSD Scale for DSM-5 (CAPS-5; Weathers, Blake, et al., 2013) as the reference standard. The PCL-5 test scores demonstrated good internal consistency (α = .96), test-retest reliability (r = .84), and convergent and discriminant validity. Consistent with previous studies (Armour et al., 2015; Liu et al., 2014), confirmatory factor analysis revealed that the data were best explained by a 6-factor anhedonia model and a 7-factor hybrid model. Signal detection analyses using the CAPS-5 revealed that PCL-5 scores of 31 to 33 were optimally efficient for diagnosing PTSD (κ(.5) = .58). Overall, the findings suggest that the PCL-5 is a psychometrically sound instrument that can be used effectively with veterans. Further, by determining a valid cutoff score using the CAPS-5, the PCL-5 can now be used to identify veterans with probable PTSD. However, findings also suggest the need for research to evaluate cluster structure of DSM-5.