The theory of self-efficacy (Bandura, 1982) has been used in the field of Information Systems to test its predictive nature of computing outcomes (Compeau & Higgins, 1995, Gist, Schwoerer & Rosen, 1989; Murphy, Coover & Owen, 1989). It has been shown to be a successful measure of performance and indeed, is now perceived as a “practical indicator of student computer competency” (Karsten & Roth, 1998). This study attempts to further quantify and qualify such a measure and investigates the degree to which self-efficacy can be manipulated. Additionally, it has been traditionally thought that programming maintenance is more difficult when a programmer must modify someone else’s program rather than his or her own. This study also investigates this phenomenon within the context of self-efficacy. Findings show that self-efficacy is an important indicator of outcome performance and that it can be artificially manipulated. Some surprising results occurred when students were asked to modify someone else’s code.