The present study examines the effects of cognitive-based metaphoric mapping instruction (MMI) on English as Foreign Language (EFL) learners' retention and awareness of figurative language at different levels of English proficiency. Ninety-one Taiwanese EFL learners participated in the study, and were separated into a control group that received no instruction in MMI and two experimental groups consisting of high-intermediate and low-intermediate learners, respectively, who did receive instruction in MMI. The results of the pretests and posttests show that MMI significantly increased EFL learners' retention and awareness of figurative language; moreover, high-intermediate learners made greater progress in noticing expressions with more abstract mapping relations. Additionally, MMI assisted learners at a lower proficiency level to acquire more advanced language ability, beyond their current level. These findings support positive claims for a cognitive perspective on second language acquisition as well as the benefits of explicit instruction in the EFL classroom.