By the 1840s, a substantial degree of orthographic standardisation of te reo Māori had been achieved, despite the fact that the first efforts to convert the language into a written form had only occurred around seven decades earlier. This trend towards greater standardisation accelerated from the mid-1810s, and was led primarily by missionaries. However, this process was occurring in an environment where there was a substantial degree of dialectical variation among speakers of te reo Māori. The ensuing standardisation of the language in text inevitably resulted in the extent of this variation being reduced dramatically. One of the consequences of this was that some distinctive pronunciation features were lost, including the ‘s’ sound which was evidently in use among some Māori communities in the Northland region of New Zealand at least (and possibly elsewhere in the country, although there is insufficient surviving evidence to verify this.By the beginning of the twentieth century, there were practically no texts being published in te reo Māori which contained the ‘s’ sound. However, some words in te reo Māori continued to be pronounced with an ‘s’ sound until around the middle of the century in a few locations in the country among native speakers of the language. It is probable, although not certain, that the standardisation of the language in print by the middle of the nineteenth century, in which the ‘s’ was removed, contributed to the decline of its use in speech (although obviously there was some lag in the effect of this). The argument could therefore be mounted that the standardised orthography of the language was contributing factor to later standardised pronunciation, although obviously, other variables were also at play. Ironically, the only ‘s’ that appeared in connection with te reo Māori, and which persisted (albeit with diminishing frequency) until the end of the twentieth century, was in the pluralisation of Māori nouns. This trend relied on the English inflection of adding ‘s’ to nouns, including nouns from languages other than English (in this case, te reo Māori).This work commences with a survey of this process of pluralisation, followed by an examination of the early history of the standardisation of the orthography of te reo Māori. The concluding section considers the evidence of the ‘s’ sound traditionally appearing in some words in te reo Māori, and the possible influence that an increasingly standardised written form of the language had on diminishing and eventually eliminating the sound from te reo Māori.