Many immigrant children might face challenges in maintaining their heritage languages--that is, continuing using their first languages (L1s) or the L1s of their parents. Factors such as pressure from schools and the desire to assimilate into the mainstream society might lead these children to learn a dominant language at the cost of losing their heritage languages. Highlighting the importance of language maintenance, this study aimed to investigate the factors contributing to the language maintenance of an Iranian individual during his 4-year stay in England. Data were collected through an in-depth, semi-structured interview, descriptive and reflective field notes during and after the interview, and the participant's journal writing. Results revealed that the participant's parents, familial attachments, frequent visits to the home country, and the L1 community were the primary reasons why the participant maintained his heritage language.