This paper presents the development, validation, and implementation of an innovative comprehensive project performance metric specifically developed for architecture, engineering, and construction (AEC) projects. The project quarterback rating (PQR) combines key performance metrics of a project into a single number to provide a basis for quantifying project success. The combined performance areas include customer relations, schedule and budget compliance, quality and safety statistics, financial metrics, and communication among the different project stakeholders. The existing literature is analyzed to identify key performance metrics. A data-collection instrument is developed and then used to gather quantitative performance data from recently completed projects. Data are collected from industry professionals across the United States, and multivariate data analysis techniques are used to validate the model. PQR can compare the overall performance for different AEC projects, in addition to the performance of various project delivery systems. In this paper, PQR scores are calculated for projects completed under different delivery systems. The results clearly show differences in performance for projects delivered with design-bid-build (DBB), construction management at risk (CMR), design-build (DB), and integrated project delivery (IPD). This paper offers three major contributions to the construction engineering and management literature: (1) it presents the development and validation of the comprehensive performance model; (2) it provides the first comparison of project delivery systems through a single comprehensive metric; and (3) it offers an evaluation of the emerging IPD system, demonstrating superior overall performance when compared with other delivery systems. (C) 2015 American Society of Civil Engineers.