The current study investigated the effect of age of acquisition and amount of language experience on children’s vowel production of the first-(L1) and second-language (L2). A total of twelve Korean learners of English varying in the amount of L2 experience (2 years vs. 5 years) participated. For L1 (Korean) and L2 (English) vowel comparisons, the spectral quality of nine English and seven Korean vowels were recorded and analyzed. The results demonstrated that the production of both English and Korean vowels varied by group. The child group with 5 years of English exposure showed more distinct separation between Korean and English vowel categories than the child group with 2 years of experience. The results suggest that late learners of L2 are likely to show a greater degree of interaction between L1 and L2 compared to early learners.