This dissertation investigates the effects of intonation, particularly boundary tones, on the timing of lexical tones in tone languages. I ask three questions: 1) Do intonation and tone differ in principle in terms of how they are integrated into the coupling which accommodates segments, lexical tones, and intonation? 2) Does the presence of intonation give rise to differences in the coordination among tones and segments? 3) Do intonation and tone interact at the phonological level or are they implemented independent of one another? A cross-linguistic production study is planned to be carried out in Mandarin, Cantonese, Vietnamese, etc. Alignment patterns in both acoustic and articulatory data will be carefully investigated.