Previous studies have shown that children’s speech is more difficult to recognize by machine than adults’ speech. This paper presents the results of experiments which investigate recognition performance variation within a small population of children. Results suggest that recogniser performance on a child’s speech is well correlated with a teacher’s assessment of the child’s speaking proficiency. For children whose speech is judged to be good, performance is close to that of adults, but error rates increase by a factor of 4 for children with ‘poor’ speech. An analysis of actual pronunciations for children with poor speech shows significant divergence from the ‘idealised’ baseforms in a pronunciation dictionary. It is demonstrated that some improvements can be gained through the use of customized dictionaries. Finally, the effects of bandwidth reduction on recogniser performance are investigated for a range of children with differing speaking styles.