Younger and older adults (mean years = 20.5 and 75) studied lists of associated words for a final recognition test. The length (5, 10, or 15 associates) and modality (auditory or visual) of study lists were manipulated within subjects. For both groups, increasing the number of associates increased illusory recollections of a related lure's presentation (measured by source judgments and the Memory Characteristics Questionnaire). This pattern suggests that associative activation of the lure influenced illusory recollection, and aging spared this process. In contrast, age impaired the recollection of source for studied words (auditory or visual) and had identical effects on source attributions for related lures. This pattern suggests that the true recollection of source influenced illusory recollection of source, and age impaired this process. To account for these and other results, we propose that associative activation drives an attribution process that binds subjectively detailed features to a false memory.