This book explores the development of the Chinese cleft construction through the lens of Diachronic Construction Grammar. Focusing on shi as an invariant copula, it examines the VP de cleft, the V de O cleft, and the bare shi cleft, showing how each signals contrastive and specificational meaning. Tracing their origins from the copular construction in Middle Chinese, the study reveals distinct developmental paths and semantic-pragmatic uses for each cleft type. Offering the first diachronic constructional analysis of Chinese cleft sentences, it sheds light on the evolution of focus structures, the expansion of constructional networks, and the typology of focus devices across languages, making a key contribution to historical linguistics and Chinese grammar research.