Children with cerebral palsy often have speech, language and communication difficulties that affect their access to social and educational activities. Speech and language therapy to improve the intelligibility of the speech of children with cerebral palsy has long been advocated, but there is a dearth of research investigating therapy effectiveness. To begin to explore the possible effectiveness of therapy focussing on speech production, six students aged 10-18 years, were given intensive individual therapy to increase breath support for speech, maintain breath support and volume across utterances and hence maximise their background effort for speech. Intelligibility of single words and connected speech was measured immediately before and after the block of therapy and again seven weeks later. Gains in intelligibility were observed at the single word level, but not for continuous speech. Implications for therapy and future research are discussed.