Patients with personality disorders are common in primary care and medical settings. They can elicit intense problematic reactions from the members of an integrated care team, which can affect the team’s evaluation, diagnoses, diagnostic testing, medical orders, medications, laboratory tests, treatments, recommendations, and referrals. The four most common and challenging personality disorders are borderline personality disorder, antisocial personality disorder, narcissistic personality disorder, and obsessive-compulsive personality disorder. This chapter reviews the classification, epidemiology, biological basis, psychosocial formulation, and co-occurring mental health disorders associated with these personality disorders. A personality disorder schema is presented for managing these difficult patients. The impact these patients can have on the integrated care team is described. A care pathway is outlined that can be used for management, brief treatment, and referral for treatment to a personality disorder specialist.