The present paper explores the hypothesis that the two phonetic systems of bilinguals are both active during processing and that these interact in real time. For this study, highly fluent early-onset bilinguals participated in two experimental sessions, a unilingual session and a bilingual session. Perception and production data were gathered. Acoustic analyses of production data show that the enhanced activation of one language affects (attracts) the sounds of the other one. These effects, however, are apparently modulated by language experience, so that interlingual phonetic interactions are more salient for some bilinguals than for others. The paper concludes by putting forth an account of these findings modeled on theories of bilingual lexical activation (e.g., Kroll & Dijkstra 2002; de Bot, Lowie, and Verspoor, 2005); in this model, the simultaneous, real-time activation of two lexicons necessarily activates the phonetic detail of lexical representations, which are responsible for the observed interlingual phonetic "system" interactions.