The rapid growth of complex projects in the construction industry worldwide has triggered a growing number of studies over the past two decades, suggesting that understanding project complexity is a key component of successful construction project management. This study aims to investigate the status and trends in project complexity research through a four-stage literature review that can benefit both researchers and practitioners. Seventy-four relevant articles were identified from studies published during the years 1996-2015, and results indicate that research in construction project complexity primarily focuses on four areas: influencing factors contributing to project complexity, the impact of project complexity, complexity measurement methods, and considerations for managing project complexity. Future research should concentrate on specific factors that drive complexity for different types of construction projects and the development of management guidelines for addressing complexity throughout the project lifecycle. This paper provides both a timely summary of literature in the area of project complexity and insights into opportunities for future study of and guidance for successfully managing complexity in construction projects.