From the outset we must distinguish between theoretical models aimed at understanding processes of social change and development and policy models that set out the ways in which development3 should be promoted. This distinction is important but not absolute, since policy models are explicitly or implicitly based upon theoretical assumptions and interpretations that are supposed to explain how change takes place or how objectives are to be achieved.4 Theoretical models may address themselves to specific dimensions (e.g. rural or urban development, or the transformation of the state apparatus and macroeconomic frameworks) and some aim to characterise the essential elements of policy-making and implementation itself. Hence we have ‘rational’ models which are based upon the belief that, by bringing more information, thought and analysis into the policy-making process, policies will become more effective; ‘disjointed incrementalism’ which regards policy-making as the science of ‘muddling through’ whereby policy-makers consider a narrow range of alternatives and respond to political contingencies as and when they arise (Lindbolm 1980); and various models that treat policy-making and implementation as inherently political processes involving bargaining and transactions between different interest groups (Warwick 1982, Palumbo 1987).5