The sustainability of any organisation depends on the retention of its employees which in turn depends on their satisfaction level. In this study the researcher had investigated the satisfaction levels of private and government school teachers handling primary children. For this research, 50 Government school teachers and 50 Private school teachers, totally 100 teachers, from different schools in Thanjavur city were examined. This study compares the satisfaction levels of the private and government school teachers based on ten variables which are found to influence them. This study also reveals that the demographic factors such as age, qualification, gender, marital status and work experience makes no difference in the job satisfaction levels of teachers. Ten factors such as Opportunity to advance professionally, Income, Recognition, Job Security, Colleagues, Working Conditions, Respect, Personal growth, Management and Immediate supervisor were considered to measure the job satisfaction and it is proved that the job security is the most significant factor among the ten factors which influences job satisfaction.