Relevance. There are a number of factors that affect students' performance in learning English. These can be both internal and external factors. The present study focuses on the internal factors that influence students' success in learning English. Theories have been put forward and research has been conducted to identify the influence of students' mental attitudes and personality characteristics. According to these theories, mental attitudes shape a person's behaviour and attitudes. Students' personality characteristics are also believed to influence their academic performance. A questionnaire covering the personality characteristics of English language learners was used for the study. The traits analysed were extraversion, introversion, openness to experience and conscientiousness. It was also investigated how these characteristics influence the level of motivation and choice of English language learning methods. Students with pronounced extraversion prefer to interact with native speakers and work in groups, while introverts prefer individual methods such as reading and writing. The results indicate a significant influence of students' attitudes and personality traits on their success. Taking into account students' personality traits can significantly improve the effectiveness of instruction by allowing it to be tailored to the needs of each learner.