Although the presence of agricultural wage labour is important for classifying farm operations and for measuring changes in agricultural structure, it has received little detailed analysis in Canada. This article attempts to redress that oversight by integrating issues that affect hired farm labour into debates about the changing agricultural structure of industrialized nations. A case study of the Ontario processed tomato industry forms the basis for analysis. Of special interest is the influence industrialization has on hired farm labour markets. When mechanized harvesting replaces hand harvesting, there are fewer workers hired per farm, child labour decreases, and there is an increase in resident female employees. This research not only contributes to our knowledge of Ontario farm workers but also provides new empirical data to support the classical Marxist model of change in the agricultural structure of industrialized nations.