Background: Until the advent of the ICD-11, classification of personality disorders was based on categorical prototypes with a long history. These prototypes, whilst familiar, were not based in the science of personality. Prototypical classifications were also complex to administer in non-specialist settings requiring knowledge of many signs and symptoms. Method: This article introduces the new structure of ICD-11 for personality disorders, describing the different severity levels and trait domain specifiers. Case studies illustrate the main aspects of the classification. Results: The new ICD-11 system acknowledges the fundamentally dimensional nature of personality and its disturbances whilst requiring clinicians to make categorical decisions on the presence or absence of personality disorder and severity (mild, moderate or severe). The connection between normal personality functioning and personality disorder is established by identifying five trait domain specifiers to describe the pattern of a person’s personality disturbance (negative affectivity, detachment, dissociality, disinhibition, and anankastia) that connect to the Big 5 personality traits established in the broader study of personality. Conclusions: Whilst new assessment measures have been and are in development, the success of the new system will rely on clinicians and researchers embracing the new system to conceptualise and describe personality disturbances and to utilise the classification in the investigation of treatment outcome.