Book excerpt: The present study aims to find out the relationship between use of the Metacognitive English Language Learning Strategies (MELLSs) for learners of English as a foreign language based on personality traits, and the role of personality traits in the prediction of use of such Strategies. Four instruments were used, which were Adapted Inventory for Metacognitive English Language Learning Strategies based on Metacognitive category of Strategy Inventory for Language Learning (SILL) of Rebecca L. Oxfords (1990), A Background Questionnaire, NEO-Five Factors Inventory (NEO-FFI), and Test of English as a Foreign Language (TOEFL). Two hundred and thirteen Iranian female university level learners of English language as a university major in Iran, were asked to participate in this research work. The intact classes were chosen. The results show that however, there is a significant relationship between four traits of personality and use of the MELLSs, but personality traits cannot be as a strong predictor with high percent of contribution to predict use of the MELLSs. (Contains 7 tables.).