Purpose - The purpose of this paper is to identify the impact of human resource development (HRD) on engineering, procurement and construction (EPC) project success (PS), human resource competency (HRC), job performance (JP), and the interrelationship among them. This paper also investigates the impact of EPC project factors (PF) on PS, the factors affecting HRD, including internal factors (IF) and external factors (EF) during EPC project implementation. Design/methodology/approach - Structural equation modeling (SEM), SPSS, and AMOS software were used to test nine proposed hypotheses. The respondents comprised 800 participants involved in EPC projects throughout Vietnam. Findings - The results show that HRD positively affects HRC, JP, and PS. HRD is influenced by IF but not influenced by EF. HRC positively impacts on JP and PS, while PF directly impacts on PS. Originality/value - The study indicates that the development of competent human resources for EPC project implementation plays a considerable role in EPC PS. The findings also give project professionals a tool for improving HRD, and HRC to increase the likelihood of PS.