To date many craterlike features have been detected in earth-based radar and Pioneer Venus imagery of the surface of Venus, but whether they are of impact or endogenic origin is still in question. The morphologic and polarization characteristics of these features, as observed from earth-based radar data obtained at the Arecibo Observatory, provide additional information that may be useful in their identification. This paper examines the extent to which this information can be used, in conjunction with our knowledge of the morphologic and polarization properties of impact craters and volcanic calderas on other terrestrial bodies, to constrain inferences about the origin of the craterlike features on Venus. Results indicate that only two features exhibit unambiguous characteristics that could tentatively distinguish them as volcanic or impact origin. However, the observed trends imply that any age of the surface derived from observed ''crater'' densities must represent an upper bound on the actual age.