The aims of this research are fi rstly, to describe the interaction<br />used by the teacher and studentsconducted in the classroomof the<br />eighth grade of SMP Negeri 18 Purworejo in the Academic Year<br />2012/2013; secondly, to know what type of interaction characteris-<br />tics of the teacher-student talk in the classroom interaction; thirdly,<br />to identify languages used in the classroom interaction used during<br />teaching-learning process.<br />This thesis is a descriptive qualitative study on teacher and stu-<br />dent talk in the classroom interaction, particularly on the partici-<br />pants’ interaction in SMP N 18 Purworejo. The data of this study<br />are the interaction between the teacher and the students in the class-<br />room. In order to analyze the data, some steps are conducted. The<br />data was taken by recording the classroom interaction. The subject<br />in this research wasthe grade VIIIG of SMP Negeri 18 Purworejo,<br />there were 40 students and one English teacher. The researcher used<br />observation and recording for collecting the data. Flanders’ Interac-<br />tion Analysis was used to identify and analyze teacher-student talk<br />in the classroom interaction.<br />The result of this study shows that the teacher was more ac-<br />tive in the interaction. Meanwhile, the student was less active than the teacher. Based on the fi nding, the researcher concludes that the<br />teacher was dominant in the classroom interaction. The percentage<br />of the teacher talk was 78.15%,whereas the students’ participation<br />was 21.16%.<br />the students<br />not balance between Indonesian<br />and English. Indonesian is 62% while English is only 38%. It<br />shows that teacher used more Indonesian than English when she<br />explains the material. The interaction was in three ways communi-<br />cation: interaction between teacher-students, students-teacher, and<br />students-students.