Significant efforts are undertaken throughout the world to reinforce the institutionalization of evaluation. As these efforts have been particularly pronounced in Switzerland, this chapter illustrates the institutionalization of evaluation within Swiss parliaments in order to inform an international discussion on the subject. In fact, evaluation today even finds an anchor in the Swiss Constitution, requiring the national parliament to ensure that the effectiveness of legal norms be evaluated. The advanced integration of evaluation into Switzerland’s legal framework may be further underscored by the high number of evaluation clauses that are contained in Swiss laws and regulations. Considering that little is known as to why parliamentarians demand evaluation clauses and what influence this ‘juridification’ of evaluation exerts on parliamentary law making, this chapter fills an important research gap by addressing these two issues. Not only does the chapter provide an exhaustive inventory of evaluation clauses contained in Switzerland’s legal corpus, it also offers an exemplary case study – that of the canton of Geneva – illustrating the formation and impact of the legal mandate to evaluate in greater detail and concludes with theoretical and practical implications for the institutionalization of evaluation from an international perspective.