This chapter begins with three clarifications. First, the markets to which it refers are electoral markets, and, within these markets, the pattern of competition with which it is concerned is inter-party competition. As is evident, parties will compete with one another when they have a market in which to compete, that is, when there are voters in competition; and the assumption which underlies the chapter, albeit guardedly so, is that the actual extent of inter-party competition, and the competitiveness of parties, is at least in part a function of the relative size of the electoral market. As the market expands, therefore, or as the number of voters in competition increases, parties are likely to become more competitive. As the market contracts, on the other hand, and as the number of voters in competition declines, parties are likely to become less competitive.