This book elaborates a theory of ellipsis that sheds new light on a well-known phenomenon, bringing it under the aegis of general and universal principles. Lobeck argues that ellipted categories in IP (VP Ellipsis), DP (N' Ellipsis), and CP (Sluicing) are empty, non-referential pronominals,subject to the same licensing and identification conditions as referential pro. She proposes that both types of empty pronominals must be licensed under head-government to satisfy the Empty Category Principle, and identified through strong agreement. In the case of ellipsis, agreement-typefeatures make the empty category visible to interpretive processes of reconstruction. These licensing and identification conditions derive the result that ellipses are complements of functional categories DET, COMP, and INFL, but not of lexical categories. The analysis is supported by contrastiveevidence from ellipsis in French and German, in which licensing and identification interact with Verb Raising, feature checking, and a parameter defining "strong" agreement.