BACKGROUND: Donor retention poses a significant problem to blood collection agencies around the world. Previous research using an augmented theory of planned behavior (TPB) approach has demonstrated that attitude, subjective norm, self-efficacy, moral norm, anticipated regret, donation anxiety from prior blood donations, and self-identity as a blood donor predicts experienced donors' intentions and that intentions, self-efficacy, moral norm, and anticipated regret may impact upon people's actual blood donation behavior. STUDY DESIGN AND METHODS: Established blood donors (n = 263) completed questionnaires assessing standard TPB constructs, anticipated regret, moral norm, donation anxiety, and self-identity as a blood donor. Three months later, a second questionnaire assessing blood donation behavior in the intervening 3 months was mailed and returned by 182 donors. RESULTS: With structural equation modeling, the final augmented TPB model provided an excellent fit to the data and included a direct path from intention to behavior and indirect paths to behavior through intention for attitude, self-efficacy, and anticipated regret. Moral norm, donation anxiety, and donor identity indirectly predicted intention through attitude. In total, 51 percent of the variance in donors' attitudes, 86 percent of variance in donors' intentions, and 70 percent of the variance in donors' behavior were accounted for in the final model. CONCLUSION: An augmented TPB framework proved efficacious in determining the predictors of the intentions and behavior of established blood donors. Further, this framework highlighted the importance of considering in the future how donors' motivations for donating blood may evolve as a function of the number of prior donations.