Cloud computing, big data analytics, mobile and social networking have had a transformative impact on firms during the last decade. The range ofopportunities presented by such new information technology inspired companies across industries to put their digital transformation at the top of their strategic agendas. In this context, a new senior executive role has recently gained prominence - the Chief Digital Officer. The emergence of Chief Digital Officers is indicative of a new organizational dynamic in firms, which recognizes the strategic importance of making the digital transformation a corporate priority.The goal of this dissertation is to give insights into the particularities of the new position, thereby progressing scientific literature on digital transformation and giving guidance to practitioners. This dissertation specifically targets Chief Digital Officers in the service sector industries, where they have been primarily established during the first years. To gain a comprehensive picture, a set of case studies examines the managerial roles that Chief Digital Officers perform, their cooperation with Chief Information Officers and the organizational structures that Chief Digital Officers are embedded in.