This study deals with the Definiteness Effect (DE) in Chinese you existential sentences from pragmatic perspectives and the scope is confined to the formal written style with discourse environments. The data used for analysis is the United Daily News Corpus and the data selection is restricted to the definite NPs which are considered unacceptable in you existential sentences: proper names, pronouns, demonstratives, universal quantifications, most-NPs, and superlative. The data for analysis in this study consist of 119 natural occurrences and the results reveal that definite NPs can occur in you existential sentences and the contexts where they appear consist of adjunct clauses and complement clauses embedded under the matrix verb. It is also observed that you existential sentences can assert the existence of entities or events and definite NPs can represent given information. I suggest that the Definiteness Effect is a misnomer and the restriction imposed on you existential sentences is derived from the non-application of ¡§identification¡¨ in existential sentences. Definite NPs are only allowed in you existential sentences when they are used to identify the entities. If the postverbal NPs are to introduce or present the entities into the discourse, definite NPs are ruled out. In addition, it is argued that if the definite NPs are anaphoric and thus given information, they are used to draw the addressee¡¦s attention to the presence of entities or events; namely, they serve as focusing topics. It seems odd to view them only as topic-introducing constructions.