We extended self-determination theory by examining personality antecedents and self-regulatory consequences of perceived locus of causality (PLOC), which is the extent to which individuals perceive their actions as caused by internal or external reasons. We theorized that personality would influence PLOC and that individuals with internal PLOC would engage in more self-regulatory activities, which would in turn predict performance and enjoyment. We used structural equation modeling with data collected from 260 students at 4 time points to test our hypotheses. The model fit the data well. Although personality had direct effects on the self-regulatory activities of effort and meta-cognitive strategies, in addition to the indirect effects via PLOC, tests confirmed that including the indirect effects produced the best-fitting model.