AbstractBoth contractual and relational governances affect building information modeling (BIM) collaboration and implementation (BCI) to improve project performance. However, the mechanism by which these governances and their interaction influence BCI remains undetermined. Considering transaction cost economics and social exchange theories, this study aimed to investigate the extent of the effect of contractual and relational governances and their interactions on improving BCI. We developed a series of hypotheses and a questionnaire to achieve the aims of the study. The partial least-squares structural equation modeling was applied to analyze the cause–effect relationship arising from the hypotheses. The results show contractual and relational governances affect BCI positively. Contractual governance, which consists of monitoring elements in safeguarding provisions, positively affect BCI and project performance. However, there is no effect found for safeguarding provisions that define the rights of parties in the contract. The study also reveals that contractual governance does not influence relational governance in BCI. This research provides new insights to project managers on the use of effective governance mechanisms to deliver BIM-enabled megaprojects for improving project performance.