The Pengo verbal system provides evidence for a new model for addressing the basic issues of the existence and nature of underlying representations (URs). Much current thinking about URs in morphological paradigms dates back to Kenstowicz and Kisseberth (1977). They claim that abstract URs are necessary to explain systems like Pengo, because no surface form can reliably generate all the other forms in the paradigm. The author shows that Pengo in fact supports a restrictive "single surface base" theory of URs like that of Albright (2002).