Previous research has demonstrated a distinction between syllable-timed languages and stress-timed languages. Because English is stress-timed language and Cantonese a syllable-timed language, Cantonese learners of English are faced with a problem of having to acquire a speech rhythm that is different from the one in their first language. While numerous other studies have shown that language transfer happens in second language acquisition and a lot of research has been done on the speech rhythm of first language speakers and mature second language learners, not much has been done on second language learners in their relatively earlier stages of language acquisition. The present study investigates the development in speech rhythm by teenage second language learners using quantitative, acoustic methods. It is commonly expected that second language learners’ speech rhythm should get closer to stress-timing with time and more exposure to the target language. Experimental data appear to be in support of such a tendency. However, due to a relatively small sample size and therefore large margins of error, the results are only indicative and not statistically conclusive. In addition, contrary to previous research, intervocalic intervals and unnormalized acoustic metrics have been found to be unstable and unreliable in characterizing the speech rhythm of younger second language learners due to their variations in speech rate as well as unfamiliarity with different words. ; published_or_final_version ; Linguistics ; Master ; Master of Arts