ICD-11 introduces a new diagnosis of complex PTSD and a fundamentally new approach to personality disorders. The two diagnoses share substantial features including impairment of self and interpersonal functioning and emotional dysregulation. This review outlines the overlap and boundaries between ICD-11 definitions of Complex PTSD and Personality Disorder. A set of principles related to trauma, onset, emotion dysregulation, self and interpersonal functioning, and dissociative and psychotic-like states are put forward to guide practitioners.