The healthcare context characterized by various groups of actors with different objectives and interests has been described as pluralistic (Denis, Langely and Rouleau, 2007). In this complex context we study the social process of how performance measures are made persuasive when different actors have distinctive views and interests about healthcare practice and performance measures. Drawing on the concept of hardening games (Rowe, Shields and Bimberg, 2012) and framing from Actor-Network Theory (Callon, 1998) we present a longitudinal field study of the development and use of a new performance measurement system by nurses in a hospital. We study how operational quantitative measures already available became more persuasive through the addition of soft measures of nurse welbeing.