This dissertation seeks to deepen understanding towards language change by answering three questions: What is the unit of change? What is the manner of change? What are the factors of change? Three cases of linguistic innovation in the Chinese language are examined. Adopting a usage-based approach, I analyze the language data of these three linguistic innovations, and the results provide unanimous answers to the three questions. First, the basic unit of language change is a construction, and it can be of any length, such as phrasal, clausal or discourse-length. Second, these cases of linguistic innovation present a scenario of change led by high-frequency exemplars, demonstrating that language change can be abrupt rather than gradual. Third, the external factors giving rise to the exemplars prove crucial in reconstructing language change in progress. All three case studies present linguistic innovation as a response to a changing material reality. I thus advocate a usage-based constructionist approach that considers external factors in the investigation of language change, as it allows us to develop a more comprehensive understanding of the process.