The purpose of this four-year longitudinal study is to investigate the main factors and processes of becoming an English underachiever. For this, a total of six participants were involved in case studies that used classroom observation, interviews, and basic English skills test as data collection methods. The five students in different grades were continuously investigated to look at the processes of learning English from both cognitive and affective perspectives. Findings of the case study showed that most participants began to face difficulty in learning English from basic reading skills, particularly in understanding English phonics. Also, four participants had negative perceptions and attitudes towards learning mainly because they feared making errors or mistakes. Lastly, some of the participants ended up withdrawing from learning English at an early stage and refused to participate in classroom activities. Based on these case study findings, the present paper identified three key factors that cause underachievement in English and how it becomes intensified over time. This paper concludes by asserting a number of implications and suggestions to prevent these problems to educational bodies and schools.