Although multisource assessment of posttraumatic stress disorder (PTSD) is considered best practice, past studies have either compared convergence between clinician interview and self-report or self- and close other collateral report of PTSD symptoms without clinician interview. Familial and interpersonal relationships are consistently found to be associated with an individual's psychological recovery following a traumatic event. Thus, it is important to understand the extent to which close others' collateral reports converge with clinician and self-reports of PTSD. This study compared self-, collateral, and clinician reports of PTSD symptom severity. Recently trauma-exposed individuals (N = 117) were assessed using the Clinician-Administered PTSD Scale (CAPS; Blake et al., 1995) and completed the past-month PTSD Checklist-Specific Stressor (PCL; Weathers, Litz, Herman, Huska, & Keane, 1993). Close others (N = 117) completed the PCL for close others (PCL-CO; Monson, 2012) that assessed their perceptions of the trauma-exposed individual's PTSD symptoms. There were significant positive correlations among PCL, PCL-CO, and CAPS total and symptom cluster scores (rs = .36-.80). Correlations were significantly stronger between clinician and self-report ratings than self-report and collateral ratings. The weakest correlations were between the PCL and PCL-CO assessing hyperarousal symptoms, r = .36, p < .01, and CAPS and PCL-CO assessing intrusive symptoms, r = .37, p < .01. Self-report measures may provide reliable PTSD assessment when clinician semistructured assessment is unfeasible. Convergence between close others' collateral and clinician and collateral and self-assessment was comparatively weak. Hyperarousal and intrusive symptoms may be more difficult for collaterals to observe and report. (PsycInfo Database Record (c) 2021 APA, all rights reserved).