This study examined the construct validity of narcissistic personality disorder (NPD) by examining the relations between NPD and measures of psychologic distress and functional impairment both concurrently and prospectively across 2 samples. In particular, the goal was to address whether NPD typically "meets" criterion C of the DSM-IV definition of Personality Disorder, which requires that the symptoms lead to clinically significant distress or impairment in functioning. Sample 1 (n = 152) was composed of individuals receiving psychiatric treatment, whereas sample 2 (n = 151) was composed of both psychiatric patients (46%) and individuals from the community. Narcissistic personality disorder was linked to ratings of depression, anxiety, and several measures of impairment both concurrently and at 6-month follow-up. However, the relations between NPD and psychologic distress were (a) small, especially in concurrent measurements, and (b) largely mediated by impaired functioning. Narcissistic personality disorder was most strongly related to causing pain and suffering to others, and this relationship was significant even when other Cluster B personality disorders were controlled. These findings suggest that NPD is a maladaptive personality style which primarily causes dysfunction and distress in interpersonal domains. The behavior of narcissistic individuals ultimately leads to problems and distress for the narcissistic individuals and for those with whom they interact.