In this paper the complexity of the modern state is examined with reference to the pressures under which it operates, and the mechanisms it employs of differentiation and integration. The reasons for the very large increase in the size of the state in this century, both in the developed countries and in the developing countries, are examined, as also some differences in the patterns of growth of the state in these two sets of countries. The major forces shaping the state in the 20th century are briefly discussed, resulting in the evolution of four models of the state. These are: the democratic interventionist-welfare state, commonplace in many Western societies; the developmental state that evolved in the Soviet system, and spread with some modifications to many developing countries; the liberal, market-friendly state espoused by the World Bank which has found a footing in most developing countries that have taken structural adjustment loans from the World Bank and IMF; and the businesslike, managerial state promoted by Margaret Thatcher, Ronald Reagn and others. It is contended that innovations in any kind of state can, with suitable modifications, be adapted in any other kind of state, and that innovations in governance systems and adaptive borrowings are powerful keys to state excellence.