For SMEs, responsiveness to changes is a critical survival capability. Practitioners believe that IT infrastructure flexibility contributes to responsiveness, yet empirical evidence is sparse. The purpose of this research is to empirically test the relationship between IT infrastructure flexibility, which is measured on four dimensions, and IT responsiveness. Two research questions are answered by this study: first, are all the flexibility factors needed to achieve IT responsiveness and second, how does each IT flexibility dimension affect IT responsiveness. According to resource-based theory, we speculate that among the four IT flexibility dimensions, only modularity and IT personnel competency have direct impact on IT responsiveness. Industrial data were collected and analyzed using PLS. The findings support our hypotheses.