This paper reports the initial results from a project designed to track the evolution of industrial and corporate structure of EU manufacturing alongside the ongoing European integration process. At the heart of the work is the construction of an "EU market share matrix" for 1993. This includes estimates of the turnovers of a set of 300 leading manufacturing firms, disaggregated across nearly 100 industries, and then, in turn, across the individual member states. This allows us to estimate the extent of diversification and intra-EU multinationality for each of the firms, and the concentration of producers and measures of geographical concentration for each of the industries. When coupled with a similar matrix for 1987, first reported in Davies, Lyons et al (1996), this provides a rich and detailed mapping of how these structural dimensions have changed with the final stage (so far as the legislation is concerned) of the European single market programme. In effect, our work provides a complement to the EC's own evaluation (1996) which was derived mainly from published aggregate data on FDI, trade and mergers. In contrast, our work is more micro-based, using company accounts and emphasising industrial structure.