This letter to the editor responds to a recent EJPT editorial and following commentary which express concerns about the validity of the ICD-11 complex PTSD (CPTSD) diagnosis. Achterhof and colleagues caution that latent profile analyses and latent class analyses, which have been frequently used to demonstrate the discriminative validity of the ICD-11 PTSD and CPTSD constructs, have limitations and cannot be relied on to definitively determine the validity of the diagnosis. Ford takes a broader perspective and introduces the concept of 'cPTSD' which describes a wide ranging set of symptoms identified from studies related to DSM-IV, DSM-V and ICD-11 and proposes that the validity of the ICD-11 CPTSD is in question as it does not address the multiple symptoms identified from previous trauma-related disorders. We argue that ICD-11 CPTSD is a theory-driven, empirically supported construct that has internal consistency and conceptual coherence and that it need not explain nor resolve the inconsistencies of past formulations to demonstrate its validity. We do agree with Ford and with Achterhof and colleagues that no one single statistical process can definitively answer the question of whether CPTSD is a valid construct. We reference several studies utilizing many different statistical approaches implemented across several countries, the overwhelming majority of which have supported the validity of ICD-11 as a unique construct. We conclude with our own cautions about ICD-11 CPTSD research to date and identify important next steps.