It is hoped that this discussion of MPD will discourage stereotypic thinking about this condition and encourage the inclusion of MPD in virtually all differential diagnoses. The major thrust of what has been learned about the natural history of MPD is that most patients with this condition spend most of their lives not manifesting their MPD in classic manner. The typical presentation of MPD is the tip of a rather large iceberg. Covert and other nonclassic presentations are much more characteristic. An appreciation of this will help the clinician approach the diagnosis of MPD with a heightened sensitivity to the possibility of encountering it within his or her practice.