Of the four skills of English, writing is probably the most difficult to teach because it requires some independent competences in vocabulary, grammar, punctuation, semantics, and rhetoric skills, etc. Most importantly, students have to integrate those competences all together into the writing. In Taiwan, college students also have already received English education for at least 6 years before entering college. Why can’t they write, at least, a grammatical essay after six years of study in English? Why do they have problems with punctuation marks? It seems that learned competence does not necessarily output good performance. Therefore, we have to reflect on the traditional writing programs which always emphasize grammar drills and the writing product. Some studies indicate the paired work or cooperative learning is better than individual learning. Is that applicable to all kinds of courses and is cooperative learning more helpful for each student than learning individually? This study tried to find out the answer. After one-year research, the researcher employed one-way ANOVA using SPSS13.0 for Windows with the significance level of 0.05 to analyze the quantitative data. The researcher found that four different types of grouping did make a difference. Individuals were grouped as either a high achiever or a low achiever. The other three types of cooperative groups, i.e., paired groups, were formed with one high achiever and one low achiever in one group, two high achievers in one group and two low achievers in one group. It was found that high achievers in individual groups progressed more than two high achievers in the paired groups. Of all paired groups, the groups formed with one high achiever and one low achiever together performed the best accounting for six of the eight students who successfully advanced into a higher level of writing at the end of the study. Low achievers, even in individual groups with the personal instruction, could not make much progress as expected. Only one of them could advance into a higher level of writing after this study. As for qualitative analysis, their learning motivation and the drive of achievement became much stronger with time. According to a self-report questionnaire after the study, 21 students thought their writing has improved than before. 24 students liked the way writing was taught, but 13 still lacked confidence in writing.