This article analyzes the associations between leadership, implementation of information and communications technology (ICT) innovations, and performance. Reviewing theories and empirical evidence from the literature on leading change, ICT innovations and performance hypotheses are formulated and tested in an analysis of the implementation of an ICT innovation in a Danish multi-site hospital. In a quasi-experimental research design using panel data, survey responses from more than 2000 employees before and after the implementation were generated as well as qualitative interviews with change agents. The findings indicate how differences in leadership during the ICT implementation process can have an important impact on performance after the ICT implementation process. The mobilization of initial support; directive leadership through information and technical assistance; participative leadership through employee involvement; and locally adapted implementation processes are important leadership factors associated with performance. We discuss the broader perspectives of our study and suggest implications for practice, theory and future research.