Integrated project delivery (IPD) is an emerging construction project delivery system that collaboratively involves key participants very early in the project timeline, often before the design is started. It is distinguished by a multiparty contractual agreement that typically allows risks and rewards to be shared among project stakeholders. Because IPD is becoming increasingly popular, various organizations are expressing interest in its benefits to the architecture/engineering/construction (AEC) industry. However, no research studies have shown statistically significant performance differences between IPD and more established delivery systems. This study fills that missing gap by evaluating the performance of IPD projects compared to projects delivered using the more traditional design-bid-build, design-build, and construction management at-risk systems, and showing statistically significant improvements for IPD. Relevant literature was analyzed, and a data collection instrument was developed and utilized in detailed interviews to gather quantitative performance data from 35 recently completed projects. Univariate data analyses, such as t-tests and Mann-Whitney-Wilcoxon tests, were performed to evaluate IPD performance. The results indicate that IPD achieves statistically significant improvements in 14 metrics across six performance areas: quality, schedule, project changes, communication among stakeholders, environmental, and financial performance. The major contribution of this paper is demonstrating that IPD provides higher quality facilities faster and at no significant cost premium. These results would be extremely valuable in the hands of decision makers to enable them to choose the appropriate delivery system for their projects.