Treating narcissistic personality disorder (NPD) successfully is possible but requires a thorough understanding of the pathology and appropriate clinical procedures. Perfectionism is one prominent feature often associated with narcissistic difficulties. Metacognitive Interpersonal Therapy (MIT) for NPD adopts manualized step-by-step procedures aimed at progressively dismantling narcissistic processes by first stimulating an autobiographical mode of thinking and then improving access to inner states and awareness of dysfunctional patterns. Finally, adaptive patterns of thinking, feeling, and acting are promoted, together with a sense of autonomy and agency and a reduction of perfectionistic regulatory strategies. Throughout, there needs to be constant attention to regulation of the therapy relationship to avoid ruptures and maximize cooperation. We describe here a successful case of MIT applied to a man in his early 20's with narcissism, perfectionism, and significant co-occurrence of Axis I and Axis II disorders.