The development of argumentative writing skills is a crucial aspect of academic achievement. However, many learners struggle to effectively structure and articulate their arguments. This study explores the use of an Argumentative Writing Checklist (AWC), grounded in the Classical Model of Argument, as a tool to enhance students' argumentative writing abilities. The research investigates how the AWC helps students improve their writing structure, coherence, and overall argumentative quality. A sample of 100 high school students participated in a pre- and post-assessment of their argumentative writing before and after using the AWC. Results suggest significant improvements in students' ability to present well-structured arguments, use persuasive language effectively, and maintain logical coherence. The findings demonstrate the efficacy of the AWC as a practical tool for fostering argumentative writing skills among learners.