This document presents a study that examines the effectiveness of developing students' extensive reading skills to improve their writing ability. The study uses a pre-experimental one group pre-test post-test design with 34 eleventh grade students in Indonesia. Students were given a pre-test to assess their initial writing skills, then received instruction focusing on extensive reading development. After the treatment, students took a post-test to evaluate any changes in writing ability. The study aims to determine if there is a significant difference in students' writing scores before and after the extensive reading instruction. Statistical t-tests will be used to analyze the data and test the hypothesis that extensive reading can positively impact writing ability.