This study examines the impact of interaction enhancement (IE) on the learning of English articles. IE is a treatment that guides learners to focus on form by providing interactional modifications and leads learners to produce modified output within a problem-solving task (strategic interaction). Two different IE treatments were employed: IE plus formal debriefing (IEF), and IE plus meaning-focused debriefing (IEM). Outcomes of these treatments were compared with the effects of non-enhanced interaction in a quasi-experimental study involving 91 Japanese EFL learners. Progress was measured with a pretest and two post-tests, yielding these major findings: (1) IE had positive effects on the learning of English articles; (2) the IEF treatment had a greater impact than the IEM treatment.