The current study compared the effectiveness of computer-delivered task-essential practice coupled with feedback consisting of (1) negative evidence with metalinguistic information (NE+MI) or (2) negative evidence without metalinguistic information (NE–MI) in promoting absolute beginners’ (n = 58) initial learning of aspects of Latin morphosyntax. This study measured language development on a variety of dependent measures (three comprehension-based tests and one production test), assessing both changes in accuracy and reaction time as well as examining effects on trained (old) vs. untrained (new) items. Although participants under both conditions improved in accuracy and reaction time on all measures, on immediate post-tests, participants receiving metalinguistic information outperformed those who did not. However, this advantage had largely dissipated by the time of the delayed tests. Performance on untrained items also suggests an advantage for metalinguistic feedback on system learning and on transfer of skills from comprehension-based practice to production. Furthermore, we argue, based on findings in cognitive neuroscience, that greater maintenance of gains in accuracy as well as evidence of some faster processing by participants not exposed to metalinguistic information may reflect qualitatively different learning processes at work: more explicit learning in the [NE+MI] group and more implicit learning in the [NE–MI] group (Li, 2010).