In this case study we present the course of the psychotherapy of Myriam, a 19-year old female with a severe personality disorder and comorbid eating disorder. During the initial assessment she reported high levels of neuroticism that parallel the diagnosis of obsessive-compulsive personality disorder, borderline personality disorder, and anorexia nervosa. Myriam showed a severely impaired personality functioning defined by perfectionism, self-criticism, interpersonal guilt and overcontrol. Her daily experience was shaped by a self-recriminative inner dialogue associated with maladaptive patterns in the form of food, water and sleep restrictions, self-harm behaviors, and suicidal ideation. She accessed an integrative treatment based on individual (Evolutionary Systems Therapy) and group psychotherapy (Mindful Compassion for Perfectionism). At the end of 14-month intervention she remitted from all the categorical diagnoses and showed reliable changes in several measures. These outcomes were maintained at 3-month follow-up. We describe the integrative conceptualization based on Myriam’s perfectionistic self-recrimination patterns, and the consequent treatment that targeted these patterns rather than focusing on symptom reduction exclusively.