The COVID-19 crisis dramatically impacted how academic classes were taught. The present two studies used two-wave prospective longitudinal designs (following two separate cohorts of university students) to examine the predictive role of the Big 5 personality traits of openness to experience and conscientiousness on students' engagement in online classes. Students were asked to report on their levels of motivation and self-efficacy for engagement in online classes. Results suggest that during the Fall 2020 semester the trait of openness to experience may have allowed students to be more engaged in online classes. However, openness to experience was no longer associated with greater engagement during the Winter 2021 semester. Instead, during this second online semester, conscientiousness emerged as the best predictor of heightened engagement in online classes. Interestingly, results suggest that openness to experience and conscientiousness may have different pathways: the benefit of openness to experience was mediated by intrinsic motivation whereas that of conscientiousness by self-efficacy.