Interface management (IM) is an emerging construction management practice that industry finds necessary for megaprojects that have become more complex and global. Defined as the appropriate management of communications, relationships, and deliverables among stakeholders, effective IM is integral to project success. Yet, because it is an emerging discipline, IM implementation has varied widely across the industry. Furthermore, the effect of IM on project performance is still unclear. To address these gaps, the construction industry institute (CII) chartered a research team, to identify the current state of IM and to investigate the relationship between systematic IM and project performance. To accomplish this, the authors conducted structured interviews for 46 projects. The study results showed that IM practices are most often found in industrial projects, with dollar values of more than one billion. In addition, IM adoption is positively correlated with the project dollar value and number of interface stakeholders. In terms of performance, projects with systematic IM tend to have lower mean and less dispersed cost growth, compared with projects without systematic IM. These results contribute to an understanding of the potential benefits of IM and its appropriate application as it further develops and is used in practice. (C) 2015 American Society of Civil Engineers.