Personnel in non-governmental organizations working for the Karen ethnic groups in Chiang Mai Province were mostly married males aged between 31 and 40 years with education lower than a bachelor’s degree. Their working experience ranged from one to ten years with a salary ranging from 5,001 to 10,000 baht. They were area operation officers and worked for religion-based organizations. Their job satisfaction was at a high level in terms of job descriptions, working environment, responsibilities, supervision, welfare, salary, and relationship with their colleagues. Their satisfaction was at a low level regarding policies and organizational administration as well as job-related promotions. In general, these personnel were satisfied with their jobs at a high level. Important factors affecting their job satisfaction included salary, welfare and working environment respectively. The above research findings revealed that these personnel were satisfied with the factors at a high level, particularly the salary factor tending to have more influence over their satisfaction. As a consequence, administrators should incorporate these factors into their administration for better job satisfaction and more efficient performance of their personnel.