A 10-year-old boy with autism was part of an evaluation of an innovative intervention focused on improving communication skills. His school was using the minimal speech approach (Potter and Whittaker, 2001) with all children in accordance with government guidance. The pupil's receptive language had not been formally assessed due to his lack of cooperation in tests and his perceived low ability. Informal assessment indicated that the pupil had restricted receptive language and school targets included understanding of basic verbs. Researchers adopted the use of "full" language and stimuli including written words to engage the child and to investigate motivation and competence. Post intervention the boy demonstrated better understanding of complex language and literacy skills than previously expected. Blanket adoption of the minimal speech approach and the low expectations of staff may lead to children's abilities being underestimated. (Contains 5 tables.)