This book reviews latest research on the effectiveness of the chief information officer (CIO) in organizations and its impact on IT success. It presents a model of six different roles, in which a contemporary CIO can act: technology provider, strategic supporter, business thinker, innovation driver, integration advisor, and relationship manager. The book analyses the effectiveness of the CIO role based on four antecedents: CIO personal competence, CIO hierarchical position, the management environment, and the IT infrastructure of the organization in which the CIO operates. Altogether the literature review synthesizes the results of highly fragmented work related to CIO role effectiveness reported in 98 studies published during the past three decades. The book contributes to information systems literature by integrating what is known about the scope and responsibilities of CIO organizational roles in the present management context, and by guiding research and practice in revealing how and why CIOs can achieve effectiveness in the six roles. The book concludes with a discussion of the limitations of the study and potential avenues for future research.