The present study used meta-analysis to evaluate the role of self-identity in the theory of planned behavior (TPB). Altogether, 40 independent tests (N = 11607) could be included in the review. A large, sample-weighted average correlation between self-identity and behavioral intention was observed (r+ = .47). Multiple regression analyses showed that self-identity explained an increment of 6% of the variance in intention after controlling for the TPB components, and explained an increment of 9% of the variance when past behavior and the TPB components were controlled. The influence of self-identity on behavior was largely mediated by the strength of behavioral intentions. Theoretical implications of the findings are discussed.