The Peer Assessment Collaboration Evaluation (PACE) Tool is an original peer assessment tool designed and developed by the authors to address the prevalence of social loafing in group projects in online learning environments. Online group projects offer students collaborative opportunities to engage in critical thinking and problem-solving. Students' participation and learning in online group projects are negatively impacted by social loafing. A total of 104 students completed all study requirements, and their data were used in the final analyses. One-way repeated-measures ANOVAs revealed significant positive main effects of PACE Tool use on participants' attitudes, subjective norms, perceived behavioral control, and related subcomponents. Students' use of the tool increased their behavioral intent to engage in peer assessment in the future may reduce social loafing in group projects, thereby positively influencing academic performance. Instructors' use of the tool may combat negative connotations associated with group work and social loafing, creating learning environments for effective group projects.