This study examined input enhancement and second language (L2) vocabulary learning while exploring the role of "distinctiveness," the degree to which an item in the input diverges from the form in which other items in the input are presented, with regard to the nature and direction of the effects of enhancement. In this study, English-speaking first-semester L2 Spanish learners studied lists of 24 new Spanish words along with their first language (L1) translations in English. In Experiment 1, one list of the words had 9 of 24 words enhanced, and the other list was unenhanced. In Experiment 2, one list of the words had 3 of 24 words enhanced, and the other list was unenhanced. Four posttests were administered to provide immediate and delayed measures of L1-to-L2 and L2-to-L1 recall. Only the results of Experiment 2 revealed significant effects for enhancement, suggesting that distinctiveness may moderate the effect of enhancement to some extent. The results of Experiment 2 for the enhanced group also indicated better performance on a proportional measure (target words learned divided by all words learned) for enhanced items and lower performance for unenhanced items. These findings support the need to examine distinctiveness and bidirectional effects in future research on input enhancement.