This paper presents the results of an empirical study conducted to refine the writers’ previous findings on potential factors that may influence performance of commercial Web-based project management systems (WPMSs) and potential measures that might be used to assess performance of such systems. Data used in this study were obtained from 39 professionals who had practical experience with WPMSs in construction projects. The results of the study confirm 42 factors that can potentially affect performance of WPMSs and 36 measures that can be used to evaluate such performance. These 42 factors are categorized into four distinct groups: characteristics of the project, the project team, the service provider, and the specific WPMS system used in the project. The 36 measures reflect performance of WPMSs in six different perspectives: strategic, schedule/time, cost, quality, risk, and communication. Findings presented in this paper can be used by researchers as a starting point for future research in the area of WPMS implementation and performance evaluation and may be used by practitioners in the industry as a useful guide to increase the likelihood of a successful WPMS adoption.