Longitudinal and cross-sectional survey data were gathered from a total of over 2,900 potential marrow donors who were at one of two critical decision points in the process leading to donation (DR-blood-typing, CT-blood-typing), and from personnel at the 100 NMDP donor centers. These data allowed the investigators to (a) describe the distribution and interrelationships between donor center structural characteristics and the strategies centers utilize for volunteer recruitment and retention, (b) determine which donor center factors (both structural and tactical) and volunteer background characteristics best predict positive volunteer-specific psychological outcomes at later typing stages, and examine and revise models of individual volunteer-specific outcomes and aggregate across-center retention rates.