AbstractPublic and private organizations are distinct in terms of ownership structure and stakeholders because they approach project management processes and structures differently. Thus, it is likely that they operate project oversight structures such as a project management office (PMO) differently and focus on a diverse set of functions. This study is dedicated to investigating PMO functions in these two cohorts of organizations to highlight their functional contrast through a quantitative survey in the Australian construction industry. The sample includes PMO units in high-performing organizations delivering successful projects in the construction industry. A literature review was conducted to identify possible functions followed by an empirical survey to solicit expert comments on the importance of each function. The results of an independent-samples t-test revealed a significant difference in the importance of three functions including (1) benchmarking best practices, (2) project management compliance, and (3) project governance, which indicate a distinction between the underpinning role that PMOs play in the public and private sectors. Following this test, the relative importance index (RII) was calculated to compare the importance level of functions and rank them across two sets of public and private organizations. The unique value that this work contributes to the construction engineering and management global community includes (1) exploring similarities and differences of PMO practice in the public and private sectors and (2) revealing the most important PMO functions in high-performing organizations, which can be applied to enhance the chance of PMO success. The findings address a research gap in the literature and contribute to the extant body of knowledge on how to configure effective PMOs in the construction context.