This book develops a grammar model which accounts for discourse ellipses in spoken Norwegian. This is a previously unexplored area, which has also been sparsely investigated internationally. The model takes an exoskeletal view, where lexical items are inserted late and where syntactic structure is generated independently of lexical items. Two major questions are addressed. Firstly, is there active syntactic structure in the ellipsis site? Secondly, how are discourse ellipses licensed? It is argued that both structural and semantic restrictions are required to account for the empirical patterns. Discourse ellipses can be seen as a contextual adaptation. Ellipsis is only possible in certain contexts. The existence of ellipsis may lead to the impression that syntax is partly destroyed. However, the analysis shows that narrow syntax is not affected. The underlying structure stays intact, as the licensing restrictions concern only phonological realization. Hence, the grammar of discourse ellipses is best characterized as an interface phenomenon.