Taxometric and biometric analyses were conducted on 2 North American samples to investigate the prevalence and biometric structure of pathological dissociation. Results indicated that approximately 3.3% of the general population belongs to a pathological dissociative taxon. A brief 8-item self- report scale called the DES-T can be used to calculate taxon membership probabilities in clinical and nonclinical samples of adults (a SAS scoring program is provided for this purpose). The genetic and environmental architecture of pathological dissociative symptoms was explored by conducting a biometric analysis on DES-T ratings from 280 identical and 148 fraternal twins. The findings suggest that approximately 45% of the observed variance on the DES-T can be attributed to shared environmental influences. The remaining variance is due to nonshared environmental influences.