At least in the realm of fast parsing, the mass–count distinction has led the life of a wallflower. We argue in this paper that this should not be so. In particular, we argue, both theoretical linguistics and computational linguistics can gain by a corpus-based investigation of this distinction: Computational linguists get more accurate parses; the knowledge extracted from these parses becomes more reliable; theoretical linguists are presented with new data in a field that has been intensely discussed and yet remains in a state that is not satisfactory from a practical point of view.