Relevance. The relevance of the study lies in the fact that in the modern world, trilingual education is becoming increasingly common, necessitating the exploration of methods, exercises, and approaches to reduce interference phenomena in language learning. Purpose. The purpose of the study is to identify factors contributing to cross-language interference in trilingual education and to develop strategies and methods for its prevention and minimisation. Methodology. To achieve the purpose, the following methods were used: hypothetical-deductive, questionnaire, correlation analysis, and comparative. Results. Results revealed key factors influencing cross-language interference across Russian, Kazakh, and English languages. They cover various language levels such as vocabulary, grammar, phonetics, as well as sociocultural aspects. The study highlights various methodological strategies and approaches that can be successfully applied to prevent cross-language interference, emphasising the active role of both learners and educators in the prevention process. Comparative analysis of English language instruction within trilingual education revealed that the majority of errors in oral and written language usage were linked to native language interference. It was also established that the degree of development of the relevant skills of students in both groups increased. However, in the first group, the growth rate reached an average of about 50%, while in the second group, the shift ranged from 25% to 38%. Conclusions. The study concludes that preventing cross-language interference in trilingual education (Russian, Kazakh, and English) requires targeted strategies and methods. Key factors influencing interference include vocabulary, grammar, phonetics, and sociocultural aspects. Effective prevention involves active participation from both learners and educators, with a focus on methodological strategies tailored to the specifics of trilingual education. Keywords: lexical skills; linguistic system; instructional materials; exercises; speech interaction