The language teacher, like the theoretical linguist, has the job of explaining or accounting for deviant, unacceptable, or odd-sounding utterances by means of grammatical rules. Thus both have the common goal of an adequate description of language, and it is this notion of combining the criterion of adequacy from both a theoretical and applied point of view that forms the basis of error grammar. Error grammar clearly challenges the traditional view that theoretical and pedagogical grammar are separate, though related, disciplines that cannot be integrated in a single approach. To accomplish this integration it is necessary to reject the notion of 'rule of grammar' as a theoretical construct and reinstate the notion of rule as an explicit guideline for conscious linguistic behavior. In other words, the grammatical rule is no longer conceived as a theoretical model of how we interpret and act upon linguistic signs, but as a map or glossary that aids us in our interpretation and action. Whether or not and to what extent the specific rules presented here measure up to this pragmatic criterion is one question that can be asked at this point, but the more important question is: How can the rules be improved? If this study serves as the point of departure for further discussion of this question, it will have achieved its purpose.