This study investigated the long-term effectiveness of explicit versus implicit instruction in a classroom setting. The participants were 114 Dutch secondary school students learning English as an L2; a control group received explicit and an intervention group received implicit instruction in a meaning-based context for two academic years. Instructional effects were measured via a timed writing task. The writing products of the two groups were compared in terms of holistic quality, writing complexity, accuracy and fluency. The results revealed that explicit and implicit instruction were equally effective in terms of promoting global writing proficiency, writing complexity and fluency. Regarding accuracy, interesting differences were found in the learners’ command of tense/aspect related verb phrases. The findings suggest that the benefit of explicit instruction lies in the use of correct verb forms, whereas the benefit of implicit instruction lies in the correct choice of tense/aspect in the communicative context.