This study examines the relationship between efficacy beliefs and task engagement in and over time, at both the individual and collective levels. We conducted latent growth curve analyses using data from 372 university students (individual level) who were assigned to one of 79 e-work groups (collective level). The participants carried out three collaborative tasks in a laboratory setting. Results reveal, at both levels, that the level of task engagement of participants and groups with high initial levels of efficacy beliefs remained stable, whereas the level of task engagement of participants and groups with low initial levels of efficacy beliefs decreased significantly over time. Moreover, the relationships linking the parallel constructs were functionally equivalent across levels. Theoretical and practical implications are discussed from the perspective of Bandura's social cognitive theory.