Based on an explorative study of sectoral training systems, this paper looks at the opportunities and limitations of a sectoral approach to training from the perspective of the knowledge economy. After the definition of the sector concept, the paper presents a theoretical analysis of the main elements and processes of sectoral training systems, considered as dynamic social systems unfolding in time through joint interactions of sectoral agencies and bodies. Four basic elements are described: sectoral agencies and bodies; training agreements between agencies; sectoral training policies and provisions; and training activities at the level of the firms. A discussion of these four basic processes follows: articulation, negotiation, policy creation, and implementation. An overview is given of the actual state of affairs in Belgium, France, and the Netherlands, three countries with well-developed sectoral training systems in a number of branches. Discussed next are the opportunities of sectoral training systems in relation to the educational system and in relation to employment and innovation, such as flexibility of the educational system, adaptation of qualifications, reduction of unemployment, and transfer of innovations. The paper concludes with a discussion of the main limitations of a sectoral approach to training. (German, English, and French versions appear in side-by-side columns. (Contains 15 references.) (YLB)