Younger (mean age = 23.9 years) and older (mean age = 73.9 years) adults were compared on a free recall task with lists of categorizable words. One-half of the subjects were given instructions to rehearse overtly during list study, and the remainder received standard (covert) instructions. Relative to covert rehearsal, overt rehearsal did not appear to affect the type of study strategy used by subjects. Age differences in free recall and category clustering were found, paralleled by clear age differences in rehearsal strategies. Young adults' rehearsal was active, serially organized early in a list, and then categorically organized for the rest of a list. Older adults' rehearsal was inactive and essentially nonstrategic, consisting mostly of single mentions of each list item. These results also show that direct strategy measures provide more information about the processes underlying age differences in memory than do outcome measures alone.