Network theory, which conceptualizes psychiatric disorders as networks of interacting symptoms, may provide a useful framework for understanding psychopathology. However, questions have arisen regarding the stability and generalizability of network analytic methods, with some researchers arguing that symptom networks have limited replicability. The aim of this study was to evaluate assessment modality as one possible source of instability in the estimation of posttraumatic stress disorder (PTSD) symptom networks. We estimated two cross-sectional DSM–5 PTSD symptom networks in 378 U.S. veterans: one using data from a clinician-rated assessment instrument (Clinician-Administered PTSD Scale for DSM–5; CAPS-5) and one using data from a self-rated questionnaire (the PTSD Checklist for DSM–5; PCL-5). We calculated centrality indices, conducted community structure analyses, and compared the strength and structure of the networks. The CAPS-5 and PCL-5 symptom networks were highly similar, challenging the notion that network methods produce unreliable results due to estimations consisting primarily of measurement error. Furthermore, each network contained distinct symptom communities that only partially overlapped with the DSM–5 PTSD symptom clusters. These findings may provide guidance for future revisions of the DSM, suggest hypotheses about how PTSD symptoms interact, and inform recent debate about replicability of psychopathology symptom networks.