The article summarizes results from a study investigating the role of aptitude on initial learning of Latin morphosyntax. The study includes two different computerized conditions: with or without metalinguistic information, provided during input-based practice with right/wrong feedback. Four aptitude measures were included: linguistic analytic ability, rote memory, working memory, and phonological short-term memory. The results revealed that linguistic analytic ability gave learners an advantage under the metalinguistic information condition when processing sentences for meaning, although only working memory (and rote memory to a lesser extent) had a role in development of grammatical sensitivity to the form. In contrast, except rote memory in immediate aural interpretation, none of the aptitude measures predicted learning under the nonmetalinguistic information condition.