High-frequency words are recalled better than are low-frequency words, but low-frequency words produce higher hit rates in a recognition test than do high-frequency words. Two experiments provided new date on the phenomenon and also evidence relevant to the dual process model of recognition, which postulates that recognition judgments are a function of increments in item familiarity and of item retrievability. First, recall and recognition by subjects who initially performed a single lexical decision task were compared with those of subjects who also gave definitions of high-, low-, and very low-frequency target words. In the second experiment, subjects initially performed either a semantic, elaborative task or an integrative task that focused attention on the physical, perceptual features of the same words. Both experiments showed that extensive elaborative processing results in higher recall and hit rates but lower false alarm rates, whereas word frequency has a monotonic, linear effect on recall and false alarm rates, but a paradoxical, curvilinear effect on hit rates. Elaboration is apparently more effective when the potential availability of meaningful connections with other structures is greater (as for high-frequency words). The results are consistent with the dual process model.