Background: Social loafing (SL) has a detrimental impact on cooperative learning. SL dysfunctionalities are causing more faculty to avoid assigning group projects as part of their course work. Aims: This qualitative case study examines how students' personalities are expressed in social loafers' behavior during university-level group assignments at a Texas university. The case study added further depth and breadth to current literature on SL in cooperative learning by exploring the perpetrator's personality expressions. Sample(s): Ten faculty members were interviewed, 32 students were surveyed, and 10 loafers were identified and self-assessed. Methods: A qualitative case study was used to provide in-depth investigation of Big Five personality in SL behavior. Results: The faculty interviews and students' surveys revealed that Openness to Experience and Conscientiousness were not expressed in SL behavior for university-level group assignments assessed by four IPIP facets. Openness to Experience (values, ideas, actions, and fantasy) was not expressed. Faculty and students indicated that loafers were not curious, barely prepared, with very short attention spans after which they get lost. Social loafers showed no originality, no active imagination, and no deep thinking. Conscientiousness (achievement striving, dutifulness, competence, and order) was not expressed. For Extraversion, Agreeableness, and Neuroticism, some facets were expressed, and others were withheld. Conclusion: The results of this study provide faculty with a multifaceted understanding of students' personality traits to better guide their group interaction and cooperative learning.