Although child labor was a widespread phenomenon in the pre-industrial Dutch economy, we do not know very much about it. This article aims to expand our knowledge by looking at children's work in several urban industries in the Dutch Republic. By investigating the kind of economic activities children performed, their starting age, working and living conditions and the amount of training they received, we want to typify pre-industrial child labour more specifically. Did children's work serve as a necessary source of wage income, or rather as a vocational training for their later participation in the labour market? It will appear that this characterization as ‘work’ or ‘training’ depended largely on the child's age, sex and social background. These distinctions may help further research on the performance of preindustrial economies, in which a demand for flexible labor played a crucial role.