AbstractThis case study investigated the relationship between classroom instructions, socioeconomic status, and English as a second language (ESL) achievement among selected upper secondary school students from different socio-economic status, gender and ethnic groups in the district of Teluk Intan, Perak. It utitilized a survey research design with emphasis on the correlational method of analysis. Based on the findings of this study, the results indicate that there is a significant difference in the mean scores of the academic performance between male and female students. Therefore, there is a statistically significant difference in the academic performance of students learning English from different gender groups. On the other hand, there is no statistically significant relationship between the students perception of the effectiveness of classroom instructions and their academic performance in learning English. In addition, there is no statistically relationship between the students socio-ec.....