The use of mental operations as recognition cues was investigated. Two experiments support the hypothesis that processing details are retained in memory and that a re-creation of those processing details can effectively cue recognition. Four subjects performed a mental arithmetic task that emphasized speed and accuracy while discouraging memorization of the numbers. Recognition was cued either by single numbers or by a pair of numbers that, when added, replicated an episode of the original task. Reprocessing an episode was the most effective recognition cue. Of the two single-number cues, the intermediate subtotals were recognized, whereas the numbers that had been physically displayed were not. The study suggests: (1) that the sequence of mental operations is retained in memory, (2) that reprocessing uses this trace to facilitate performance, and (3) that the detection of facilitated reprocessing aids recognition.