This article investigates the role self-efficacy plays in the relationship between Neuroticism and foreign language attainment (operationalised as final grades and self-perceived foreign language skills). To date, the role of personality in foreign language learning has not been clearly specified; moreover, self-efficacy related to this domain has not received sufficient attention. For the purpose of the paper it was proposed that the negative relationship between Neuroticism and attainment can be explained by self-efficacy. The study's informants consisted of 495 secondary grammar school students at the intermediate to upper-intermediate levels of English proficiency. The results revealed that L2 (domain-specific) efficacy fully mediated the weak, though statistically significant link between Neuroticism and self-perceived L2 skills. It is argued that one's beliefs in their capacity to effectively manage the foreign language learning process may play a crucial role in understanding the relationship between Neuroticism and L2 attainment.