In his book Ancient Slavery and Modern Ideology (1980) Moses Finley argued that chattel slavery only started to become a major force in the Roman world after the official abolition of nexum in 326bc (or 313BC, as some would argue) had made it impossible to exploit the labour of Roman citizens. In other words, the drying up of one source of exploited labour led to a more intensified pursuit of another pool. In reviews of Finley's book scholars occasionally questioned the validity of this argument, but no systematic investigation of the relationship between the abolition of nexum and chattel slavery in fourth-century Rome has been undertaken so far. Finley's argument has in fact become the standard interpretation of the development of slavery in early Rome. In this chapter I shall try to do two things. Firstly, I shall argue that the abolition of nexum in 326 BC is misleading shorthand for a complex phenomenon on which we are very poorly informed. What can be established with some degree of certainty is that the Senate responded to the excesses accompanying nexum rather than establishing its concern with the procedure itself. Secondly, I shall re-examine the evidence supplied by the historian Livy (59 BC-AD 17) for the number of captives enslaved by the Romans during the Third Samnite War (298-290 BC), which formed the basis for Finley's argument that chattel slavery rose to a level unprecedented in Roman history, and demonstrate that the argument is difficult to substantiate.