Peer Tutoring is a widely used method of teaching English. Peer tutoring, a pedagogical strategy that has the potential to assist Indonesian advanced students in developing inferential understanding by combining it with KWL charts, has, however, received little attention in the context of Indonesian EFL (English as a Foreign Language). The aims are first to know the implementation of peer tutoring and KWL Charts in reading. Second, to know whether or not there is a significant difference in students' inferential understanding. Third, to know the factors affecting students' inferential understanding. Fourth, to know the students' attitudes toward the role of PT integrated with KWL charts in developing inference skills. For these purposes, 54 advanced students participated in the project. This research utilizes a mixed-method design, combining (a) one group pretest-posttest design, with (b) a qualitative study. The researcher uses various data collection methods, including pretest-posttests, interviews and questionnaires. The paired sample t-test was used to interpret the quantitative data. To analyze qualitative data, the researcher uses descriptive analysis. The study shows that peer tutoring integrated with KWL benefits students' positive attitudes toward reading comprehension. Moreover, there is a significant difference in students' inferential understanding when using peer tutoring integrated with KWL.