This study examines the effects of the integrated reading-writing tasks (e.g., writing summaries or reflective essays) on college students’ writing performance. A pre-test and a post-test which consisted of reading comprehension questions and a writing task were administered to 207 EFL college students at the beginning and end of a semester. The data was analyzed both quantitatively using ANOVA and post-hoc test, and qualitatively using a questionnaire survey and interviews. The mean scores of the posttest for the classes which utilized the integrated reading-writing tasks were higher than that of the control group. Also, higher level students in the two experimental groups and a control group showed that there were improvements between the pre-test and post-test, specifically in the treatment groups. The analyses of the questionnaire survey and interviews revealed that the treatment groups which integrated reading-writing in class perceived writing summaries and reflective essays as helpful and effective tools for enhancing their writing ability. The overall results of the study indicated that implementing the integrative approaches to language instruction in the EFL classroom is beneficial in improving learners’ writing performance regardless of the learners’ proficiency level.