This document outlines a thesis proposal that aims to enhance students' critical thinking in writing. Specifically, it will conduct classroom action research at the diploma level to address issues students have with clarity, accuracy, precision, relevance, depth, logic, and significance when writing report texts. The research methodology will involve setting and subjects, data collection techniques like observation and tests, and data analysis. The importance of critical thinking, integrating it into the classroom and writing, and previous related studies are also discussed. The overall goal is to help students become more critical writers by developing their ideas and applying universal intellectual standards.