This study investigates the pluralisation of words in three phonologically disordered children to determine whether they select plural endings on the basis of their own erroneous surface forms of word-stems or on the basis of internal representations which are closer to the adult forms than the surface forms suggest.Results suggest that: a) The procedure used can provide valuable information about children's internal phonological representations and could be of clinical value. b) In the subjects tested there are instances where internal representations of words are shown to be closer to the adult forms than the children's surface forms would imply. However there is evidence that their internal representations are not always exactly equivalent to the adult forms. GRUNWELL, P. et al-mix GROUP (1980) Progress report: the phonetic representation of disordered speech. Brit. Journ. Dis. Comm. 15,215-220. IVIMEY, G. P. (1975) The development of English morphology: an acquisition model. Languageand Speech. 18,120-144. JOHNSON, s. and SOMERS, H. (1978) Spontaneous and imitated responses in articulation testing. Brit. Journ. Dis. Comm. 13, 107-1 16. MILLER, w. R. and ERVIN, s. (1964) The development of grammar in child language. In Bellugi, U. and Brown, R. (eds), The acquisition of language. Monog. SOC. for Res. in Child Devel. 29. Chicago: Chicago University Press.