AbstractIt has been a weakness of some clinical applications of segmental feature analysis that they fail to discriminate between the general phonetic and strictly phonological aspects of the model. The result is that classificatory features have often been inappropriately employed in speech assessment as phonetic notation devices, a function they are much too abstract to fulfil adequately. In this paper, an attempt is made to demonstrate the value of a two‐stage clinical analysis which clearly distinguishes between the phonetic and phonological dimensions of features. The approach is illustrated through the case study of a five‐year‐old whose production exhibits the effects of what can be termed articulatory weakening. At a phonetic level, a feature analysis based on degree of airflow resistance can be exploited to elucidate the articulatory dimensions of the child's disorder. The insights gained at this stage can subsequently be interpreted in terms of more abstract, classificatory features in order to ascertain the implications that the deviant articulations have for the child's ability to signal the phonological contrasts of normal adult lan