Aging is associated with task-specific changes in eye movements, and thus eye movements during mind wandering (MW) in older adults may differ from young adults. We showed that changes in number of fixations or fixation duration were associated with MW in young adults when searching for information but not older adults, possibly due to aging-related changes in these measures. Similarly, larger variance in pupil diameter change was associated with MW when imagining a scenario in young but not older adults, possibly related to aging-related affect stability. In contrast, lower eye movement consistency was associated with MW when implementing well-learned visual routines in older but not young adults, possibly related to their higher susceptibility to MW interferences. Reduced joint attention with another participant was associated with MW for tasks involving clearly defined strategies for both young and older adults. These results have important implications for monitoring task engagement through eye tracking.