Background: Although psychological disengagement is a well-documented phenomenon in the academic setting, the attempts to identify its predictors are scarce. In addition, existing research has mainly focused on chronic disengagement and less is known on the determinants of situational disengagement. Aims: The purpose of the present study was to identify the predictors of situational disengagement in a physical education (PE) setting. In line with the core postulate of psychological disengagement, it was hypothesized that grades contribute to discounting through a decrease in perceived competence. Drawing upon self-determination theory, it was also expected that devaluing reflects the motivational orientations of individuals. Sample: A total of 120 students who were in seventh, eighth, and ninth grades. Method: Students were asked to report their motivation towards PE and their perceived competence at the beginning of a 10-week cycle. Perceived competence in PE and psychological disengagement were assessed at the end of cycle, after grades were communicated individually to each student. Results: The results revealed that grades significantly predicted discounting, through perceived competence, but did not predict devaluing. Devaluing was negatively predicted by integrated and identified regulations, and positively predicted by amotivation, whereas no motivational variables were related to discounting. Conclusion: The present study extends the core postulate of psychological disengagement to situational disengagement. It revealed that students may temporarily disengage their self-esteem from performance feedback through discounting, but are less inclined to devalue the academic domain when faced with negative feedback in a particular situation because of their motivational orientations.