Free time to attend to and process information in working memory is key in promoting immediate and delayed retention. One candidate process to cause this benefit is elaboration. We conducted three experiments with young adults – two of which included older adults – to investigate whether free time is used for elaboration, and whether elaboration causes the free-time benefit. Participants remembered lists of nouns, interleaved with short or long free-time intervals, or with filler words connecting all the nouns into a meaningful sentence to assist elaboration. For young adults, assisted elaboration through sentences, and the additional instruction to form a mental image, benefited performance in a working-memory test as much as longer free time, but not more. In contrast, for a delayed test of long-term memory, the benefits of sentence elaboration exceeded those of longer free time. Older adults did not benefit from assisted elaborations in the delayed test, providing further evidence that the long-term memory deficit of older adults arises at least in part from a deficit in elaboration. This elaboration deficit is not driven by a deficit in generating richer representations.