Volume IX of the second edition of The Cambridge Ancient History has for its main theme the process commonly known as the "Fall of the Roman Republic." Chapters 1-12 supply a narrative of the period from 133 B.C. to the death of Cicero in 43 B.C., with a prelude analyzing the situation and problems of the Republic from the turning-point year 146 B.C. Chapters 13-19 offer analysis of aspects of Roman society, institutions and ideas during the period.

It is about Roman law in its social context, an attempt to strengthen the bridge between two spheres of discourse about ancient Rome by using the institutions of the law to enlarge understanding of the society and bringing the evidence of the social and economic facts to bear on the rules of law.