There were six components to the study. The first identified significant factors influencing regular blood donations by individuals with different donation histories - first-time, second-time, committed (frequent), and lapsed donors. The second component developed and assessed the validity of behavioral models to increase donor retention and to predict whether first and second time donors would contribute again. The third developed donor-retention interventions, especially for the first and second time donors. The fourth component identified homogeneous subgroups among first, second and committed donors who might be receptive to different types of intervention strategies to increase the frequency of their donations. The fifth component evaluated the success of cost-effectiveness of the new interventions compared to existing blood center maintenance strategies. The sixth identified whether or not donors had a limit or ceiling on how often they donated per year.