This is an investigation into the grammaticalized system of focus-background agreement in Mandarin Chinese. The particles cai, ji., dou and ye are, in a specific use type, shown to form the core of a highly systematic paradigm. Foci agree with their backgrounds, with the particles being the agreement markers. The semantic categories involved are different types of quantification over alternatives: all alternatives may be true, or some, or not all, or none. This minimal semantics is capable of explaining the use of cai, ji., dou, ye and two more particles (hai and zai) in various contexts that have figured in controversial debates over the past three decades. This book is not just a valuable companion for anyone interested in core aspects of Mandarin Chinese grammar. It caters for the interests of theoretical linguists as well as for linguists from other fields with an interest in information-structure, focus and contrastive topics, and quantification. The outstanding characteristic of this book, viz. its effortless integration of findings from formal semantics without heavy formal load, makes it rewarding reading both for linguists with a less formal background, and for researchers with some knowledge of formal semantics.