This study explores the growth mindset and self-regulatory capacity of Korean college students during English vocabulary acquisition. It also identifies the relationships between these variables and the students’ lexical proficiency levels. A total of 193 students participated in the study and were classified into three groups based on their word knowledge: high-, medium-, and low- achieving learners. Four research instruments were used: a background questionnaire, the Growth Mindset Scale in Vocabulary Learning (GMSVL), the Self-Regulating Capacity in Vocabulary Learning (SRCvoc), and a vocabulary levels test. The results show that high-achieving learners exhibited significantly greater outcomes than the medium- and low-achieving learners in terms of commitment belief and positive self-talk on the GMSVL. Additionally, high achievers displayed significantly stronger outcomes than low achievers in terms of commitment control and metacognitive control on the SRCvoc. Significant associations were found among growth mindset, self-regulatory capacity, and vocabulary skills. Based on the results, the present study suggests adopting more supportive teaching methods and provides specific examples.