The authors review the existing literature on the relationship between education, training and employment in the urban traditional sector of the economy - also called informal or unstructured sector - which represents 30 to 60% of the urban labour force. They start with a discussion of the various theories concerned with the origin, role and evolution of the traditional sector in a developing economy. They analyse the results of existing studies in Africa, Latin America and Asia which draw the profile of the "standard worker" in the traditional sector. They then examine the role of formal education and informal apprenticeship in the development of the traditional sector and their impact on its productivity. Apprenticeship, which in many countries plays the dual role of imparting the necessary skills to workers and providing cheap manpower, thus allowing the reproduction of this subsistence sector, in a clear example of the complex relationship between education and employment.