This article reports on a classroom-based study that investigated the effectiveness of direct written corrective feedback in relation to learner differences in grammatical sensitivity and knowledge of metalanguage. The study employed a pretest–posttest–delayed posttest design with two treatment sessions. Eighty-nine Greek English as a foreign language (EFL) learners were randomly assigned to 3 groups: direct feedback only, direct feedback plus metalinguistic comments, and comparison. The linguistic target was article use for specific and generic plural reference. A text summary and a truth value judgment test were employed to measure any development in learners’ ability to use articles. The results revealed an advantage for receiving direct feedback over no feedback, but provided no clear evidence for the benefit of supplying metalinguistic information. Additionally, participants with greater grammatical sensitivity and knowledge of metalanguage proved more likely to achieve gains in the direct feedback only group.