Compared to other aspects of language teaching, second language writing is a relatively new field. However, there are still many unanswered questions. Of all the dilemmas related to L2 writing pedagogy, perhaps the most important and problematic is the question of how we can facilitate the improvement of our students' writing ability (CPC p. 94). Feedback is a key part of teaching second language writing, with instructors spending considerable time and energy providing feedback on written errors in EFL learners' compositions. The value of providing feedback on correcting errors is often not highly appreciated, even though it is quite widely practiced. Researcher Lee (2009) cites many researchers who view written responses as frustrating (Ferris et al. 1997), grueling and anxiety-inducing (Stern and Solomon 2006), and tedious and thankless (Hyland 1990). Most teachers would not mind this effort if they believe it helps improve students' writing skills. Due to the nature of correcting written errors, it is a very laborious undertaking, consuming much of the time and energy of both teacher and student, both in and out of the classroom . However, does the written corrective feedback on the compositions of L2 students contribute to developing their abilities to improve their writing and to become independent self-publishers of their own writings? The purpose of this literature review is to examine the cost-benefit of teachers' response to grammatical errors in second language writing and to reach a conclusion on the best approach. Cost-benefit analysis is more commonly used in business circles, but I believe is relevant in the analysis that follows. Teachers and learners face many difficult decisions regarding course assignment...... middle of copy...... the indefinability of these standards precludes the possibility of simply hear about a definition of good writing and teaching. once and for all, as one might follow a cake recipe. (p.40 Leki) I completely agree with Lei's suggestion that we explain as explicitly as possible what good writing is, but understand that there is still so much that is implicit and therefore difficult to use for students. Consider that improvements in writing may be the result of other variables, for example in students' grammar class, or the result of extensive/intensive reading. As one researcher states, their studies are criticized for being short-term and if they take a longitudinal approach, they are criticized for a lack of control. It is generally agreed that it is problematic to research the effect of feedback on written errors on future writing assignments..