  We describe a novel technique and implemented system for constructing a
subcategorization dictionary from textual corpora. Each dictionary entry
encodes the relative frequency of occurrence of a comprehensive set of
subcategorization classes for English. An initial experiment, on a sample of 14
verbs which exhibit multiple complementation patterns, demonstrates that the
technique achieves accuracy comparable to previous approaches, which are all
limited to a highly restricted set of subcategorization classes. We also
demonstrate that a subcategorization dictionary built with the system improves
the accuracy of a parser by an appreciable amount.
