Practitioners of patient safety practice change agree that champions are central to the success of implementation. The clinical champion role is a concept that has been widely promoted yet empirically underdeveloped in health services literature. Questions remain as to who these champions are, what roles they play in patient safety practice change and what contexts serve to facilitate their efforts. This investigation used a multiple-case study design to critically examine the role of champions in the implementation of rapid response teams (RRTs), an innovative complex patient safety intervention, in two large urban acute care facilities. An analysis of interviews with key individuals involved in the RRT implementation process revealed a typology of the patient safety practice champion that extended beyond clinical personnel to include managerial and executive staff. Champions engaged to a varying extent in a number of core activities, including education, advocacy, relationship building and boundary spanning. Individuals became champions both through informal emergence and a combination of formal appointment and informal emergence. By identifying and elaborating upon specific features of the champion role, this study aims to expand the dialogue about champions for patient safety practice change.