This study investigated the relationship between language attrition, cultural identity, and sociocultural factors in four international schools in Azerbaijan. Two distinct student groups, one undergoing English education since preschool (Group 1) and another transitioning to English after primary school (Group 2), were examined to discern the connection between language attrition, cultural identity, and sociocultural factors. The research explored acculturation strategies concerning loss of proficiency in the first language (L1) and bicultural identity and formulated hypotheses to assess the connection between education level and language loss and the influence of attrition on cultural identity shift. Employing a comprehensive mixed-methods approach, the research utilized native language proficiency tests and e-surveys for quantitative analysis, while focus group interviews and thematic analysis investigated qualitative aspects. The e-survey uncovered factors influencing L1 attrition, with Group 1 exhibiting lower native language proficiency, suggesting an impact of second language (L2) exposure. Regression analysis revealed that language skills, English communication preferences, and thinking in English predicted lower proficiency in L1, while the duration of L2 exposure played a pivotal role in shaping cultural identity. Focus group interviews demonstrated a subtle narrative of cultural shift and assimilation within the international school context. The theoretical framework and thematic analysis provided a comprehensive understanding of the acculturation experiences of international school students, emphasizing the concept of culture attrition influenced by diverse factors.