Purpose: The purpose of this study is to investigate the role of social support in the experience of job stress among hospital nurses. Method: This study was carefully designed to overcome methodological shortcomings found in past research, and examined two organizational effectiveness variables(job satisfaction and organizational commitment) as outcome variables. The sample used in this study consisted of 602 nurses from 5 general hospitals. Data were collected with self-administered questionnaires and analyzed using hierarchical regression and LISREL technique. Result: It was found that: (a) three job stress variables(workload, role conflict and conflict with other medical staff) have negative effects on job satisfaction and organizational commitment; (b) social support have positive main effects on the two output variables; (c) the negative effects of job stress variables on job satisfaction and organizational commitment are not buffered by social support, and (d) social support mediates the effects of job stress on job satisfaction and organizational commitment, and the size of the mediating effects is small. Conclusion: Further research needs to be done to further refine this study.