This study examined the effect of word class (nouns vs. verbs) on L2 pronunciation accuracy of Korean-English bilinguals. The participants were 192 adult immigrants whose age of arrival (AOA) in the United States ranged from 6 to 23 years. Transcriptions of their productions of English sentences indicated that they were more accurate in pronouncing verbs than nouns. Similarly, the results of a grammaticality judgment test revealed that they were more accurate in detecting incorrect formulations of verbs than nouns. These effects were significant in late L2 learners (AOA 12-23). The results were interpreted to reflect the influence of the linguistic structure of Korean (where the verb is more prominent than the noun) on learning English as an L2.