A new organizational species is emerging--the integrated health care delivery system. Aligned with both the anticipated provisions of federal and state health care reform initiatives and emerging purchaser demands, integrated delivery systems could dominate many health care markets by the end of this decade. Integration is both the defining feature and key imperative of such systems. Because of the unique position of boards, governance is potentially the ultimate integrator. Yet little attention had been focused on integrated delivery system governance. Accordingly, this article will address the governance of integrated delivery systems through three questions: (1) What are the distinguishing characteristics of integrated health care delivery systems? (2) What are the distinctive issues and challenges associated with governing integrated delivery systems? and (3) What different forms of governance can be employed by these systems and what factors influence the effectiveness of these forms?