This paper applies autopoietic theory to examine the nature of ISñorganization relationships involving co- evolutionary processes among an organization and its IS, IS organization issues, and the impacts on an organizationís competitive advantage. By drawing on a longitudinal field study in an international investment banking organization, where the development of a core IS has been studied since 1999, this paper (1) presents the distinct characteristics of the autopoietic approach; (2) demonstrates its explanatory power for understanding the ISñorganization coevolutionary processes and IS organization, and (3) shows the implications of these autopoietic explanations for the firmís current and future competitive advantage.