The vowels of Kwakʼwala are "a, e, i, o, u, ə". There is a phonemic length distinction as well; however, not all vowels exist in both long and short versions. The phonemic status of some of the vowels in question is relatively unclear, as especially evident in the case of "a" and "ə". They often interchange in different instances of the same stem or suffix, depending on the phonological content. presents some cases of complementary distribution between "a" and "ə" but concludes that those vowels must be underlyingly distinct in some other cases.