Decision makers are more likely to passively accept than to actively reject preselected default options. Age differences in such "default effects" have not been systematically examined, but prior research reports age-related variation in several known determinants of default effects suggesting that they may be more common in older as compared to younger adults. To address this question, a representative life span sample (N = 500; Mage = 49.90, SDage = 19.34; 51% female, 49% male; 67% non-Hispanic White) responded to a preregistered online study. Participants completed a default effect task comprising two conditions, one requiring opt-out and one requiring opt-in decisions (i.e., 15 vs. 0 preselected features each). Susceptibility to defaults was assessed as the discrepancy between the number of features selected within each condition. In addition, we collected data on known determinants of default effects (i.e., perceived endowment, endorsement, ease, experience making similar choices, importance of the choice, and affective responses to the choice). Finally, we screened demographic background, personality, socioemotional and health status, and cognitive ability. Susceptibility to default effects was evident both at the individual and the group level. Unlike hypothesized, older age did not predict greater susceptibility to defaults, and older adults were less likely to endorse determinants of default effect compliance. Of the covariates assessed, only identifying as non-Hispanic White, greater perceived endorsement, greater perceived ease, and lower perceived importance of making the right choice predicted decision makers' susceptibility to default effects. Thus, our findings suggest that susceptibility to decision defaults does not vary by age. (PsycInfo Database Record (c) 2023 APA, all rights reserved).