Modified social learning theory (MSLT) applied to health predicts that health behavior is a multiplicative function of health value and perceptions of control over health. The self-management behaviors of persons with Type 2 diabetes mellitus, internal diabetes locus of control (IDLC), diabetes self-efficacy (DSE), and health value (HV) were assessed with an index of diabetes self-care activities in 107 patients receiving insulin. Multiple regression analysis showed DSE as the only MSLT construct that correlated with the index of diabetes self-care behaviors (β = .21, p < .05). While the predicted three-way interaction of IDLC × DSE × HV was significant (∆R2 = 4.5 %, p < .05) in the final step of the hierarchical model, the pattern of the findings only partially supported MSLT. Instead of finding that patients who were simultaneously high on all three predictors scored highest on the behavioral index, we found that patients who were low on all three constructs reported the least amount of diabetes self-care behavior. Implications for further modification of MSLT and its applications to clinical practice are discussed.