The present study examined the speech production of three-year-old Korean-English bilingual (KEB) children. English and Korean stops, as well as front vowels in both languages, were compared acoustically among the KEB children, then also measured against those of their age-equivalent monolingual counterparts. Evidence of distinctive phonetic categorization in bilingual children was more salient in vowels than in stops. Vowels and stops produced by the bilingual children were not significantly different from those of their monolingual counterparts. The findings suggest that, similar to other language domains, two linguistic systems are apparent in the phonetic production component of three-year-old KEB children, but that phonetic distinctiveness in production may not emerge holistically in an across-the-board fashion, appearing earlier in vowels than stops. Thus, the phonetic production systems of the two languages may develop with only limited interaction in simultaneous KEB children exposed to two languages at an early age.