Little is known about organization citizenship behavior (OCB) based on dual ratings by both nurses and their supervisors instead of the former only. Except the transformational leadership (TR) and some relevant factors, the supervisors’ recognition on subordinators’ OCB (sOCB) may affect subordinators’ OCB (nOCB) as well. The mediation mechanism on nOCB was examined, to what extent of effect was induced by supervisors’ TR and sOCB, and subordinators’ self-efficacy, team trust, and the professional commitment. It was a cross sectional, exploratory causal, and dualrating study, which surveyed 560 nurses and 27 supervisors of a medical center in southern Taiwan. Various measures were used, such as demographic characteristics, transformational leadership, selfefficacy, team trust, professional commitment, and OCB. To construct the mediation mechanism on OCB, AMOS 19.0 was employed. Evaluated by the cmin-criterion, the structural equation model of dual ratingswas of as 0.81 highfitness probability, while only 0.21 for that of supervisor-free model. The TR affected little on subordinators’ OCB individual (nOCBI) and trivial on OCB organizational (nOCBO). Emitting mediation effects on nOCBI, subordinators’ commitment, trust, self-efficacy and both OCBO and OCBI were influential factors. Besides, subordinators’ age and retention tendency induced substantially effect on nOCB. The fitted-well model revealed that, in the studied organization, sOCBO induced substantial effect on nOCB; however, TR had only little effect on nOCBI and nOCBO. The subordinators’ education had somewhat direct effect on nOCBI instead of nOCBO. With higher self-efficacy, senior subordinators acted beneficially to colleagues; and with higher professional commitment, those acted beneficially to the organization. Nursing administrators may need further examination over the appropriateness of both their OCB recognition and their transformed leadership whenever they anticipate leading their registered nurses toward a better healthcare organization. © 2015, Chinese Society for Quality. All right reserved.