Introduction An understanding of the impact of processes of European integration and corporate restructuring upon multinational manufacturing operations in Wales needs to take account not only of the sorts of markets being served by establishments but also the performance of establishments in producing for these markets. For example, it may be that whilst Welsh operations of multinationals are quite well placed in terms of serving growing mass and niche markets they may be relatively uncompetitive compared either to other parent company plants or the plants of competitor firms. Given the importance of multinationals to the Welsh economy and given the focus of this study, a key issue to be explored in this chapter is that of the extent to which Welsh manufacturing operations are effectively in competition with other parent company plants. For multinationals, in the short to medium term at least, competitive pressures in particular markets often manifest themselves not in terms of the decision to remain or withdraw from the market but in terms of decisions about where to source products from. In turn, these product sourcing decisions have implications in terms of investment and rationalisation for company plants with similar production responsibilities.