The objective of the research was to assess the factors affecting the quality of social infrastructure projects in the industrial zones in Hanoi, Vietnam ver the period 2018-2019 by means of qualitative and quantitative research methods where the quantitative research was conducted by an independent survey agency to enhance the objectivity of data. Adopting PLS - SEM method of Smart PLS, 3.0, we analyzed data from 396 valid questionnaires and the results showed that materials, design, construction and Stakeholder had positively affected the quality of Social Infrastructure Projects (SIPs). In the meantime, the project size also played a moderate role on the quality of social infrastructure projects.