Studies dedicated to examining the relationship between human resource management (HRM) and organizational performance have predominantly laid stress on the private sector firms with little studies examining international governmental organizations (IGOs). Therefore, this study examined the effects of HRM practices on the attitudes of workers in an international government organization (IGO). The study obtained the results by analyzing data from staff survey and from interview sessions in a cross-sectional study focusing on one of the fop and largest IGOs. Based on an extensive organization-wide survey supported by interview sessions, the study investigated the effects of HRM practices on the attitudes of workers. The IGO has a quasi-governmental role in delivering required public services that cover healthcare, social services, education and emergency assistance. Based on empirical evidence, there are significant effects of some HRM practices (training and development) that showed higher significance to others like staffing and recruitment. The findings showed that HRM practices do have significant effects on the attitudes of employees in a synergistic and complementary way that overcome their individual effects. This paper reached to the conclusion that HRM practices have a positive and significant effect on the attitudinal outcomes of workers. Added to this, there are factors that could have a moderating effect (positive/negative) on the practices, which is raised from the reverse causality question.