This research aimes to explain the effectiveness of Slowly Application and Peer Assessment in teaching Recount text writing. This study used a quantitative method and a quasi-experimental research design (non-equivalent group design). The participants consisted of eighth-grade pupils from SMP Negeri 18 Semarang in the academic year 2022/2023. They were the VIII-G experimental class and the VIII-H control class. Each class consisted of 32 students selected using a technique of purposive sampling. The experimental class was taught with the Slowly application and Peer Assessment, whereas the control class was presented by the teacher or taught without the Slowly application and Peer Assessment. This research instrument was a written test, and the scoring rubric for writing was used to evaluate the students' writing on the pre-test and post-tests. The results indicate that the mean post-test score for the experimental group is 78.94, with a mean gain of 16, while the mean post-test score for the control group is 76.19, with a mean gain of 14.5. Moreover, statistical hypothesis testing using an independent sample t-test revealed that on the degree of significance 5% (α = 0.05), tobserve was 2.246 while ttable was 1.999, indicating that tobserve > ttable. Therefore, the alternative hypothesis (Ha) was accepted, and the null hypothesis (H0) was rejected. The effect size of this study is 0.56, which indicates that it has a moderate impact. It can be concluded that the Slowly application and Peer Assessment significantly impacted teaching writing of recount texts.