Contract cheating – students outsourcing assignments to ghost-writers and submitting it as their own – is an issue facing tertiary education institutions globally. Approximately 3% to 11% of higher education students may engage on contract cheating. Understanding why nearly 90% of students do not engage in contract cheating is as important as understanding why other students do, as it can aid in the development of effective interventions and policies. This study addressed limitations in previous research and built upon a measure of Reasons for Not Contract Cheating (RNCC). In this study, 403 university students participated in an online survey consisting of a revised version of the Reasons for Not Contract Cheating measure (RNCC-R) and measures of psychological individual differences, such as the dark triad personality traits, self-control, and autonomy. Two higher-order factors and six sub-factors were identified in the RNCC-R, which included some similarities to the original RNCC. The findings from this study demonstrate the importance of psychological individual differences, such as satisfaction of the need for autonomy, grit (perseverance of effort), and Machiavellianism, in predicting the reasons why students do not engage in contract cheating. Consistent with previous research, this study provides support for the importance of students’ motivation for learning, and their perceived morals and norms, as reasons for not engaging in contract cheating. It additionally provides evidence of the importance of the academic environment, such as respect for academic staff, as a reason why students do not engage in contract cheating.