The use of demonstrative adverbs is a function of making reference to a real or abstract location. In German, there are three principle demonstrative adverbs that are used spatially--hier, da, and dort. This thesis provides an overview of the primary theories proposed in the literature to explain the German hier/da/dort system of reference and examines those claims from the context of a study of L2 learners and L1 speakers combined with a corpus-based analysis of the frequency, distribution, and use of the demonstrative adverbs, both in isolation and in unison. The evidence from learner data, native speaker interpretations and grammaticality judgments, adult use corpora, and L1 child corpora all point to da as playing a more significant role than dort in the three-way spatial adverb system of German. Evidence from multiple sources points to the default hier `here' counterpart, there-like equivalent being da. While da is not always used to indicate a non-speaker location, this flexibility is not an indication of its primary or default role. Context often provides semantic information, and even if used in a semi-neutral manner, the use of da often suggests the possibility of a dort-type non-speaker location or of an abstract location/third location. The flexibility that da has in being used in non-contrastive locations or idiomatic expressions to refer to the location of the speaker does not discount the role da has as a primary means of indicating spatial differences in opposition to hier. The presence of dort enables a third location to be identified with a distinct spatial adverb, while hier appears to be highly restricted in its usage. Evidence from child L1 learners is congruent with this analysis. The frequency of da in child L1 learner speech cannot simply be explained by phonetic production, and the child L1 corpora show that dort is only chosen when da and hier are already present (three or more locations are referenced). Native speaker survey data concerning the three spatial adverbs under investigation indicate that locational situation affects the acceptance and interpretation of all three adverbs including da. Da is not shown to be a superfluous double, as it is neither consistently accepted at or near 100%, nor is its acceptance consistently near that of dort or hier. There is evidence that native speaker grammaticality judgments show regional variation when da is used to indicate a speaker location, with northern speakers tending to prefer hier and southern speakers tending to prefer da. L2 speakers show a greater variation from native speakers with respect to their acceptance and interpretations of da as compared with that of hier and dort. Non-native speakers were more likely to accept hier and less likely to accept da than were the native speakers in this study. Elementary, intermediate, and advanced L2 learners showed a significant difference in their acceptance rates of da in at least 50% of the items, while the group of highly-proficient L2 speakers of German showed a significant difference in their acceptance of da in only one item.