The goal of the current study was to examine bilinguals' phonological short-term and working memory performance in their native/first (L1) and second (L2) languages. Korean-English bilinguals were tested in both Korean (L1) and English (L2). Short-term memory (STM) was measured via a nonword repetition task, where participants repeated nonwords that increased in length. Working memory (WM) was measured via a complex task, where the nonword repetition task was combined with an animacy judgment task. In general, bilinguals performed better on the STM task than on the WM task, and with shorter nonwords than with longer nonwords. Results also revealed that L1 STM performance was superior to L2 STM performance, but only for the longest nonwords, whereas L1 WM performance was superior to L2 WM performance across all length levels. In addition, correlation analyses between bilinguals' L1 and L2 performance revealed stronger cross-linguistic associations for the WM task than for the STM task. Together, the findings suggest that WM tasks may engage domain-general central executive processes in bilinguals, whereas STM skills may depend on language-specific knowledge in the L1 and the L2.