There are no convincing studies of the absolute prevalence of DID. The initial systematic report on the epidemiology of DID estimated a prevalence in the general population of 0.01% (Coons 1984). The estimated prevalence is approximately 3% of psychiatric inpatients (Ross 1991; Ross et al. 1991b). Studies conducted in the general population suggest a prevalence higher than initially reported by Coons (1984) but lower (about 1%) than the one described in psychiatric settings and specialized treatment units (Ross 1991; Vanderlinden et al. 1991). Loewenstein (1994) reported that the prevalence in North America is about 1%, compared with a prevalence of 10% for all dissociative disorders as a group. Loewenstein's findings were replicated by Rifkin et al. (1998), who studied 100 randomly selected women, ages 16–50 years, who had been admitted to an acute psychiatric hospital and found that 1% of the subjects had DID. There is evidence that dissociative disorders are often underdiagnosed (D. Spiegel 2006). Foote et al. (2006) carefully assessed 231 consecutive admissions to an inner-city mental health clinic and interviewed 82 of those willing to cooperate with the study. Twenty-nine percent of this sample met DSM-IV (American Psychiatric Association 1994) criteria for a dissociative disorder (8 with dissociative amnesia, 7 with dissociative disorder not otherwise specified, 5 with DID, and 4 with depersonalization disorder). Only 5% of this sample had previously been diagnosed with a dissociative disorder. Furthermore, the study provided additional evidence linking both physical and sexual abuse to dissociative symptoms, determining an odds ratio of 5.86 for physical abuse and 7.87 for sexual abuse. In a recent study of community adults, the prevalence of dissociative identity disorder was 1.5% (J. G. Johnson et al. 2006).