This is a study and translation of the Zhou bi suan jing, a Chinese work on astronomy and mathematics which reached its final form around the first century AD. The author provides the first easily accessible introduction to the developing mathematical and observational practices of ancient Chinese astronomers and shows how the generation and validation of knowledge about the heavens in Han dynasty China related closely to developments in statecraft and politics. The book will be of equal interest to historians of science and those studying the history of Chinese culture.