The purpose of this study was to predict job satisfaction based on emotional self-regulation and defense mechanisms in welfare workers in Tehran province. Methodology: This study was a correlational study. The statistical population of this study was all employees of Tehran's Welfare Office in 2013-2014 who were selected using a sampling method of 324 (158 men and 166 women). Data were collected by JDI, Defense Mechanisms (DSQ-40) and Difficulties of Difficulty Adjustment (DERS). The collected data were analyzed using Pearson correlation and multiple regressions. Result: Pearson correlation results showed that all components of emotional self-regulation, with the exception of emotional awareness, have significant correlation with job satisfaction. There is a significant inverse relationship between all components of emotional self-regulation, with the exception of emotional awareness, with immature defense andNeuroticism defense mechanism. Multiple regression analysis showed that emotional selfregulation explains 5% of the variance of job satisfaction, but defensive styles do not explain job satisfaction. In investigated gender difference with t test showed that, men in satisfaction with promotions, compensation and satisfaction, and satisfaction with working conditions are in higher levels of satisfaction. However, in overall job satisfaction score, there was no significant difference between men and women. Conclusion: The result of this study indicated a direct relationship between emotional selfregulation and job satisfaction, inverse relationship with unmet and unpredictable defense mechanisms and lack of relation with defense styles. Therefore, considering the importance of the ability to regulate emotions on the use of defense mechanisms and job satisfaction, one can use the guidance and therapeutic techniques of psychologists and counselors in the welfare organization to increase the awareness and gain of emotional adjustment skills and the use of the developed mechanisms in to promote job satisfaction and goals of the welfare organization.