Traditionally, historians have tended to accept the view that agricultural labourers in nineteenth-century England were subject to seasonal unemployment. In this article, however, it is argued that this is an over-simplification, and that there were in fact two coexisting labour markets. Using two sets of micro data, a wage book and the Census Enumerators' Books, it will be revealed (1) that there were two groups of agricultural labourers: those who were employed throughout the year (core workers) and those employed only in the busiest season (casual workers); (2) that the core workers and casual workers performed different tasks; (3) that they had different places of residence; and (4) that the casual workers' wages were more market-dependent. The movement of wages at the time of the arrival of Irish migrant labourers sheds further light on the different natures of the two markets. While core workers' wages appear to have been unaffected by this change in labour demand, English casual workers' and women's wages increased sensitively.