The use of information technology (IT) is becoming an essential component within the commercial sector. While large number of companies have adopted IT applications to achieve competitive advantage, and number of studies have been done on competitive advantage through an IT application, it is not clear what the impact of an IT application on competitive advantage is. The purpose of this study was to examine the impact of an IT application on competitive advantage and how to create and sustain competitive advantage through an IT application. For that purpose, this study adopted Sethi and King's (1994) instrumental tool, while the theory of resource based view of the firm (RBV) was the theoretical underpinning for the investigation of how to create and sustain competitive advantage through an IT application. In other words, this study examined how an IT application impacts the seven dimensions which are attributes of competitive advantage through an IT application, and how a firm's resources and capabilities, which are measured in three dimensions. moderate the impact of an IT application on competitive advantage. The three dimensions were identified from the review of literature concerning on the theory of RBV. / Ph. D.