Student engagement is an important factor in higher education learning, but engaging students in online learning settings has been found to be challenging. Little research has been conducted yet into how online learning activities can engage students. In this study, students' experiences with online education were examined during the COVID-19 pandemic to find out what online learning activities promoted their engagement and what underlying engagement mechanisms informed those activities. Six online focus groups were held via Zoom with students (N = 25) from different social sciences programs at the University of Amsterdam. Findings revealed synchronous and asynchronous online learning activities that stimulated three dimensions of engagement and their underlying mechanisms. "Behavioral" engagement was stimulated through activities that promote attention and focus, inspire effort, break barriers, and provide flexibility. "Affective" engagement was stimulated through activities that promote a group feeling, encourage interaction, and create a sense of empathy and trust. And "cognitive" engagement was stimulated through activities that generate discussion and personalization. This research provides teachers with insights into how to promote student engagement in online education.