The present study scrutinized the association between learners’ perceptions of EFL instructors’ interpersonal behavior and their English language achievement in Amhara regional state public universities, Ethiopia. In this correlational research, 177 participants who were first-year English Language and Literature students were selected using purposive and random sampling. The data were gathered through a questionnaire and an English language achievement test. Besides, the data were analyzed quantitatively using descriptive and inferential statistics, and multiple regression. The findings showed that understanding behavior was perceived as the frequent interpersonal behavior of EFL instructors followed by strict, student freedom, and leadership behavior, respectively. Apart from this, uncertain behavior was found to be the least perceived behavior in the classrooms. In addition, the findings indicated that instructors in the sample areas were less prevailing but more cooperative in the communique process with their learners. In line with relationships, it was found that optimistic and noteworthy correlations between students’ English achievement and their teachers’ understanding and leadership behavior. In the case of its contribution, understanding followed by leadership interpersonal behavior was found to be the most prevailing and substantial variable on the learners’ English achievement. It was, therefore, recommended that instructors should be given training continuously on instructors’ interpersonal teaching behavior and its relationship to students’ language learning.
