In the early days, the Chinese community in Malaysia lived in groups segregated by place of origin. The Chinese dialects served not only as the colloquial and everyday language of the respective communities but also as a symbol of identity. Records show that Chinese private schools existed in Malaysia as early as the beginning of the 19th century and used Chinese dialects as the mediums of instruction. In the early 1900s, the Chinese schools, under the influence from China, underwent a lengthy process of transformation, with the medium of instruction slowly transitioning from Chinese dialects to Mandarin. In the decades after, Chinese dialects and Mandarin coexisted in equal importance among the Malaysian Chinese society. In the 1980s, the Chinese society in Malaysia, following the footsteps of their Singaporean counterpart, promoted the use of Mandarin through the “Speak more Mandarin, speak less dialects” campaign, and rules forbidding the use of Chinese dialects were introduced in Chinese schools. During this period, Chinese dialects suffered a severe setback in Malaysia. The ban lasted for more than three decades, and it was not until recent years that some Chinese schools relaxed the rule and allowed the use of Chinese dialects in school. This thesis studies the usage of Chinese dialects in Malaysia under the influence of changes in societal structure and thoughts, both its current situation and future prospects. In order to gain a deeper understanding of the impact of rules forbidding the use of Chinese dialects in Chinese schools, this study took a focus on the Chinese school settings. The Pei Tsin High School in Sabah was chosen as a point of entry in view of its lack of enforcement of the Chinese dialect ban despite being a school regulation for years. In addition, the Hakka people constitutes the majority of the population in Kudat, and the use of Hakka dialect is prevalent among the local community, including in the school compound of Pei Tsin High School by the teachers and the students. By studying the use of Hakka dialects in Pei Tsin High School, insights could be gained into both the impact of the dialect ban in Chinese schools as well as the use of Chinese dialects in schools. Moreover, Pei Tsin teachers and students are of diverse ethnic origins and thus provided a rich and heterogenous sample for the study. This thesis aims to identify the crux of the problems faced by Chinese dialects and predict the threats that might arise in the future through the analysis of the current situation. The study findings revealed that Chinese schools have limited effectiveness in the promotion of Chinese dialects. As teaching and learning remain the core activities in the Chinese schools, the standard mediums of instruction such as Malay, Mandarin and English are predominantly used, with limited opportunities to communicate in Chinese dialects. The key impacts of schools allowing the use of Chinese dialects are in altering the old perceptions about Chinese dialects and in improving identification with the Chinese dialects among the school teachers and students. As the Chinese dialect-speaking ability of Pei Tsin students is more closely related to the language habits of their family and social environment, the promotion of Chinese dialects should be a collective responsibility of the Chinese community.