The DSM-5 Alternative Model of Personality Disorders (AMPD) and the ICD-11 Classification of Personality Disorders allow clinicians to describe trait domains that contribute to the unique expression of personality dysfunction. Both diagnostic systems deliniate trait domain features of negative affectivity, detachment, antagonism/dissociality, disinhibition, and anankastia/compulsivity, which may inform clinicians about how to manage treatment. This chapter specifically describes how the DSM-5 and ICD-11 trait domains may be useful for establishing a favorable treatment alliance, doing therapeutic assessment, increasing the patient’s self-knowledge, providing psychoeducation, planning realistic treatment goals, and matching therapy to the patient’s personality. A key message of this chapter is that practitioners should not treat traits per se but the maladaptive expressions of traits.