Fundamental frequency (F0) is the most important feature among the components of prosody in a language, tone and intonation languages alike. In a tone language, how lexical tone and sentence intonation can both use F0 as their main acoustic cues has long been an intriguing question. Will the lexical tones be so resistant to modification that no elaborate intonation is possible in the language? How much of the surface sentential F0 is attributable to lexical tones and intonation? If F0 modification is kept minimal, how will prosodic focus be realized? And will the lack of focus-related F0 change be a disadvantage in terms of focus perception? In this dissertation, experimental studies have been made on Cantonese in some less well-understood aspects of its prosody. Firstly, the tonal characteristics of sentence-final particles (SFPs) in Cantonese as a special case of the interaction between tone and intonation are examined. Secondly, the acoustic correlates of prosodic focus in Cantonese are explored. SFPs are a class of words known to have functions similar to intonation. It is not yet clear, however, whether the F0 contours of SFPs are derived purely from lexical tones, purely intonational, or a combination of tone and intonation. As an attempt to offer a solution, a production experiment was designed in which sentences in Hong Kong Cantonese with ten different SFPs were recorded and detailed analyses of their F0 contours, final F0, final F0 velocity and duration were performed. The results show that most of these SFPs are very similar to the lexical tones in terms of F0 contours, but there are significant differences in durations in more than half the cases. In addition, the occurrence of an SFP does not give rise to differences in F0 and duration in the syllables preceding the SFP in most cases. But differences can be seen in sentences with question SFPs, which indicates that the prosody of the SFPs may be partly due to intonational meanings. One of the SFPs, however, exhibits a component F0 contour that seems to be sequentially attached to the end of the lexical tonal component. These findings suggest that Cantonese SFPs have underlying tonal targets just like those of lexical tones, but they also carry intonational meanings by modifying the lexical tonal contours. Previous research has shown that Beijing Mandarin, a tone language, marks focus not only by on-focus prosodic expansion like many other languages, but also by post-focus compression of pitch range and intensity (PFC). However, recently it is found that PFC is absent in Taiwanese and Taiwan Mandarin, two languages closely related to Beijing Mandarin. This finding both highlights the non-universality of PFC and raises questions about its origin. The present study explores these issues by investigating focus production in Cantonese by native Cantonese speakers born and raised in Hong Kong, and in English and Cantonese by bilingual speakers who were born and raised in Southern England. Results from the Hong Kong speakers show that, just as in Taiwanese and Taiwan Mandarin, PFC is absent in Cantonese, and mean F0, duration, intensity and excursion size were found to be higher in on-focus words. Results from the bilingual speakers show that their Cantonese also lacks PFC. More remarkably, out of the fifteen bilinguals tested, only one-third show PFC in all their English test sentences. These findings suggest that PFC is hard to transmit across languages through bilingualism. Moreover, the differential prosodic patterns among the bilingual speakers suggest that in the bilingual community, PFC may be subject to gradual loss. Although tone-intonation relationship in SFPs and the acoustic correlates have previously been studied, most of the discussion lacked supporting evidence from phonetic experiments. The present study is distinguished in its systematic experimental design and detailed acoustic analyses, and it is hoped that the results will lay the foundations for future investigations into Cantonese phonetics