The aim of the paper is to consider the significance for labour law theory and practice of empirical research into the operation and effects of this branch of law. It will be argued that empirical research has an important role to play in the methodology of labour law, even if it is ancillary, much of the time, to doctrinal approaches. Secondly, and relatedly, the paper will address the historical role of empirical research in the shaping of labour law as a field distinct from both private law and public law, and, in particular, as transcending the categories of property and contract that were inherited from the individualist private law of the nineteenth century. The third and last theme of the paper is that of the role of empirical research in addressing contemporary issues of labour law doctrine and policy.