This book provides a unified analysis of the theory of economic policy, presenting static and dynamic aspects of both the fixed and flexible objective policy problems. The authors conceive of the abstract theory of economic policy as the interaction of policy possibilities with policy-making requirements. Policy possibilities are depicted by a known, linear model relating sets of targets, instruments and other variables. Policy-making requirements are imposed in two forms: directly by nominating a specific fixed target in the tradition of Tinbergen; and indirectly by specifying preferences about targets - the flexible target associated with Theil.