Positive psychology, which focuses on well-being and life satisfaction, has attracted significant attention from researchers in educational context, particularly in language learning and teaching. The aim of this study is to investigate whether grit and learned helplessness, as two emotional constructs of positive psychology, impact vocabulary learning. Three widely validated instruments-the Learned Helplessness Scale (LHS), the Grit Scale, and the Vocabulary Levels Test-were used to collect data from 155 university students (46 males, 109 females) enrolled in an English Language Teaching (ELT) department in Cyprus, employing a cross-sectional research design. Statistical analysis using SPSS version 22 revealed a significant positive correlation between grit and vocabulary size (p < 0.001). Conversely, a significant negative correlation was found between learned helplessness and vocabulary size (p < 0.001). These findings suggest that enhancing grit and perseverance while reducing learned helplessness may improve vocabulary acquisition among EFL students.