This study used causal modeling to trace the effects of manager leadership characteristics on staff registered nurse (RN) retention in 4 urban hospitals. Unique to the study were the all-RN sample, using Leavitt's (1958) model of behavior within an organization to group variables, manager characteristics and unit structure variables as predictors, and focus on the work unit rather than the hospital. Effects of manager characteristics were traced to retention through work characteristics, job stress, job satisfaction, commitment, and intent to stay. Theoretical variables explained 22% of the retention variance. Manager consideration of staff and RN intent to remain directly affected retention; other variable effects passed through intent to stay. Different predictors were important to retention, unit separation, and turnover.