This study examines the role of differences between parties involved in outsourced information systems (OISD) projects, focusing on 1) the mechanisms vendors use to manage those differences; and 2) the long term impacts of those mechanisms. Using data from a revelatory case study, we anchor our theorizing in institutional theory to develop three main propositions emphasizing 1) the role of instances of conflicting institutional demands in OISD projects; 2) the relevance of the logics driving the enactment of institutionalized practices to explain how vendors respond to those instances; and 3) the ability for those responses to trigger a process of institutional change. Offering a comprehensive explanation of the management of differences in OISD projects, our work has implications for research and practice.