The paper resumes results from an inquiry exploring the role of capability on initial learning of Latin morphosyntax. The inquiry covers two distinct computerized conditions: with or without metalinguistic information, supplied during input-based practice with right/wrong feedback. Four aptitude measures were covered: linguistic analytic ability, rote memory, working memory, and phonological short-term memory. The results disclosed that linguistic analytic skill gave learners an advantage under the metalinguistic information condition when processing sentences for meaning, although only working memory (and rote memory to a lesser degree) had a role in evolution 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.