Background/Objectives: Numerous studies have examined nursing students’ academic dishonesty; however, there is still a gap in understanding the predictors of such behavior. This study aimed to identify personal (intrapersonal and interpersonal) and contextual factors predicting nursing students’ dishonesty during clinical training. Methods: A two-phase, prospective, predictive study was conducted at a nursing faculty in Croatia. The validated “Mentor Support Evaluation Questionnaire” was used in the first phase to assess students’ evaluations of the quality of mentor support during clinical training. The validated instruments “Optimism/Pessimism Scale” and “Nursing Student Perceptions of Dishonesty Scale” were used in the second phase to examine self-reported dishonesty and its contributing factors. The second phase also investigated the students’ knowledge of the university’s ethical and disciplinary regulations. Results: Of 398 participants, 195 (48.9%) reported engaging in clinical dishonesty. Hierarchical regression analysis identified critical predictors of frequent clinical dishonesty: lack of fear of consequences (β = −0.072), positive attitudes toward dishonesty (β= −0.081), higher incidence of academic dishonesty in the classroom (β = 0.221), lack of knowledge of the university’s regulations (β = −0.349), and low quality of mentor support (β = −0.430). The final model explained 60.7% of the variance in participants’ clinical dishonesty (p < 0.001). Conclusions: The identified predictors indicate that interpersonal factors, i.e., the quality of mentor support, influence students’ clinical dishonesty more than intrapersonal factors (e.g., attitudes or knowledge). Contextual factors (healthcare employment and study overload) were unrelated to clinical dishonesty. This finding can help develop strategies to reduce nursing students’ dishonesty and improve patient safety.
