Working memory performance depends on reactivating memory traces, by rapidly switching between refreshing item representations and performing concurrent cognitive processing (time-based resource sharing account). Prior research has suggested that variation in the effectiveness of this process could be a plausible source of developmental changes in working memory capacity. This could conceivably extend to adults, potentially bridging the barrier between developmental and adult experimental research and providing a possible functional role for attention control and processing speed in working memory tasks. The present work was designed to replicate the finding of developmental differences in reactivation in children, and to test whether the same process could be related to individual differences in adults. Experiment 1 confirmed the finding of more effective reactivation for 14-year-old children than for 8-year-old children. Experiment 2 using the same task in adults manipulated the feasibility of reactivation within an experimental-correlational approach, and failed to find more effective reactivation for individuals with high working memory capacity, contrary to our predictions. Overall, our results support the role of reactivation as defined by the TBRS model as an important process in working memory tasks, and as a possible source of developmental increase in working memory capacity; but they rule out the possibility that adult individual differences in the effectiveness of this process are a major cause of variability in working memory capacity, suggesting that differences between adults are of a different nature.