Selecting the appropriate formwork system (FWS) is a critical aspect in the successful completion of reinforced concrete (RC) building construction projects. The selected FWS has a significant impact on the cost, time, and quality performances of the project. As there are many FWSs and formwork fabricators (FWFs) available, the selection of the FWS depends on several compromising and conflicting criteria. This study aims to identify the FWS selection criteria groupings (e.g., latent factors) and investigate the quantitative interrelationships among them. For this purpose, 35 FWS selection criteria were identified through literature review, and a questionnaire was developed. The data from the questionnaire were statistically analyzed, and five latent factors were identified: FWS-FWF characteristics, structural design, local conditions, cost, and performance indicators. A conceptual framework was developed based on the latent factors, and a structural equation modelling (SEM) approach was utilized to identify the effects among the latent factors. The results of the SEM approach confirmed that FWS-FWF characteristics are affected by the structural design and local conditions and FWS-FWF characteristics have a substantial effect on cost and the performance indicators of the project. The findings of this study may assist construction professionals in selecting the FWS in building construction projects.