A description of a sophisticated computer program for the syntactic analysis of natural languages. The study discusses the notation used to write rules and the extent to which these rules can be made to state the same linguistic facts as a transformational grammar. Whereas most existing programs apply context-free phrase-structure grammars, this new program can analyze sentences with context-sensitive grammars and with grammars of a class very similar to transformational grammars. The program, which is written for the IBM 7040/44 computer, is nondeterministic: The various interpretations of an ambiguous sentence are all worked on simultaneously; at no stage does the program develop one interpretation rather than another. If two interpretations differ only in some small part of a partial syntactic structure, then only one complete structure is stored with two versions of the ambiguous part. The unambiguous portion is worked on only once for both interpretations. Although the current version of the program is written in ALGOL, with very little regard for efficiency, the basic algorithm is inherently much more efficient than any of its competitors. 33 pp.