This article is a detailed account of COMLEX Syntax, an on-line syntactic dictionary of English, developed by the Proteus Project at New York University under the auspices of the Linguistics Data Consortium. This lexicon was intended to be used for a variety of tasks in natural language processing by computer and as such has very detailed classes with a large number of syntactic features and complements for the major parts of speech and is, as far as possible, theory neutral. The dictionary was entered by hand with reference to hard copy dictionaries, an on-line concordance and native speakers‘intuition. Thus it is without prior encumbrances and can be used for both pure research and commercial purposes.