The advanced relative clauses represent a grammatically interesting phenomenon, as they exhibit characteristics typical of root clauses on one hand, while behaving like typical subordinate clauses on the other. The book presents a comprehensive picture of the grammar of advanced relative clauses based on extensive empirical studies. It considers syntactic, semantic, and discourse-structural aspects equally. The author describes advanced relative clauses as non-restrictive sentences that can only be considered generally clause-related in a syntactic sense. She demonstrates that advanced relative clauses semantically refer to individuals or abstract entities of different types, mediated by an introductory w/d-anaphor. This is elaborated in detail within the framework of constraint-based grammar theory HPSG.