This article explores the acquisition of Japanese vowel and consonant quantity contrasts by Cantonese learners. Our goal is to examine whether transfer from first language (L1) is possible when L1 experience is phonemic but restricted to a small set of sounds (short vs. long vowels) and when the experience is non-phonemic, derived only at morpheme boundaries (short vs. long consonants). We recruited 20 Cantonese learners (beginner and advanced learners) and 5 native speakers of Japanese, who produced target stimuli varying in consonant and vowel quantity framed in a carrier sentence. The resultant data were converted into several durational ratios for analyses. Results showed that both the beginners and advanced learners were able to distinguish between short vs. long vowels and consonants in Japanese, but only the native speakers enhanced the contrasts in slower speech. It was also found that in most cases the learners were able to lengthen the vowel before a geminate (i.e. long consonant), a secondary cue to Japanese consonant quantity known to be rare across languages. These results are discussed in terms of current theories of second language acquisition.