This study compared school-aged monolingual and bilingual English-as-a-foreign-language (EFL) learners in terms of understanding metaphors on recall, multiple-choice, and reasoning tasks. It also examined the relationship between cognitive capacity and understanding metaphors on different measures. A hundred and thirty Persian-Turkish early bilinguals and 122 monolingual Persian-speaking EFL learners took three different tests of metaphor comprehension and the Figural Intersections Test, a test of cognitive capacity. Bilinguals outperformed monolinguals in terms of cognitive capacity and understanding metaphors on two of the tasks, though with a small effect size. Furthermore, there was a significant positive relationship between cognitive capacity and the scores on the multiple-choice and reasoning tests, but not the recall test. Results suggest that bilingual L3 learners have an edge in understanding metaphors, reflecting a cognitive advantage.