Researchers and practitioners alike have taken note of the potential value of an organization's IT infrastructure. IT infrastructure expenditures account for over 58 percent of an organization's IT budget and the percentage is growing at 11 percent a year. Some even have called IT infrastructure the new competitive weapon and see it as being crucial in developing a sustained competitive advantage. Unique characteristics of an IT infrastructure determine the value of that infrastructure to an organization. One characteristic, IT infrastructure flexibility, has captured the attention of researchers and practitioners. In fact, in most recent surveys featuring issues of most importance to IT executives, the development of a flexible and responsive IT infrastructure and related topics are always at or near the top of the responses. Although the importance of IT infrastructure flexibility has been established, the development of a valid, reliable instrument to measure this construct has not been reported in the literature. The purpose of this paper is to better define the IT infrastructure flexibility construct and to develop a valid, reliable measurement instrument for this construct. In addition to the definition and operationalization of the IT infrastructure flexibility construct, this study explores the instrument's predictive validity with possible antecedent and consequent variables.