Performance measurements are meant to improve public decision making and organizational performance. But performance measurements are far from always rational tools for problem solving, they are also political instruments. The central question addressed in this article is how performance measurement affects public policy. The aim is to conceptualize the political consequences of performance measurements and of special concern is how performance systems influence how political decisions are made, what kind of political decisions are conceivable, and how they are implemented. The literature on the utilization of evaluation and performance measurements is applied to analyse how performance measurements affect the political process of goal-setting, implementation and learning. The article concludes that performance measurements may have intended and unintended effects and they seem to have a retroactive impact on the political decision making process, as the focus on performance goals entails a kind of reductionism (complex problems are simplified), sequential decision making processes (with a division in separate policy issues) and short-sighted decisions (based on the need for making operational goals).