CorrecText, from Houghton-Mifflin, is a significant advance in grammar checkers, because it uses a full parse of sentences in its analysis. Though limited by the fact that many English sentences are syntactically ambiguous, the program can find many errors in grammar, style, and usage. Still, questions remain about where and how it can be useful. It is not terribly useful on final versions of good prose; the makers assert that it is more useful on unedited prose, where there are many inadvertent errors. An empirical study of much unedited prose would not only verify this assertion, but would help improve the program.