Public policy-making, as technocratically conceived, appears as a rational process of solving known problems. Political problems are then regarded as part of a pre-given ‘neutral’ reality to which public policy simply responds. In contrast, our contribution develops a critical approach in that it traces three different (at times overlapping) perspectives. Firstly, we introduce approaches that criticize the top-down and linear conceptualizations of policy-making as problem-solving and instead study agenda-building as a complex process of turning issues into political problems. Secondly, we present a more fundamental epistemological challenge as constituted by post-positivist approaches and their focus on the struggle over the definition of problems at various stages of the policy process. Lastly, we introduce approaches that emphasize the role of power and political manipulation in problem definition and agenda-setting. Taken together, these strands provide the basis for a critical perspective which conceptualizes problem definition as a basic discursive process – part of the construction of a political world – and agenda-setting as a specific type of problem definition that attributes responsibility to a political actor or institution. From this perspective, problem definition and agenda-setting are not regarded as distinct phases but as constructions of reality that can be identified within the larger policy-making process.