Moodle is a free, open-source, e-learning, cross-platform course management system (CMS). This article is mainly focused on how Moodle can be effectively used in a college writing classroom. First of all, the basic installation and major functions of Moodle will be introduced. Then, social constructionist view of Moodle will also be specified. Next, the vital features related to writing instruction will be detailed. After that, the reasons to choose Moodle at Chung Hua University will be briefly talked about. Finally, the article will conclude with the possible technical difficulties and pedagogical challenges that teachers of English writing may face if they would like to use Moodle in the collegiate writing classes.