It is practically universal, in contemporary works dealing with te reo Māori (the Māori language) to observe that there is no ‘s’ sound in the language. This applies to plural forms of nouns (for which there is a tendency in English, when it comes to foreign nouns, to pluralise by adding an ‘s’) and in the vocabulary more generally. This article investigates the evidence for the claim that in some Māori dialects, the ‘s’ sound was used historically, and explores a range of possibilities for the consonant effectively disappearing from spoken te reo Māori by the middle of the twentieth century, and much earlier from written forms of the language.