In the UK there is much concern about the educational progress of children from areas of significant social disadvantage entering primary school with impoverished language skills. These children are not routinely referred to speech and language therapy services and therefore education practitioners in schools deliver intervention to facilitate their language learning. The evidence base to support these interventions is small and more needs to be known about their effectiveness. However, evaluating such interventions in an educational context can be challenging due to limited opportunities and resources. The study evaluated small-group language intervention for Key Stage 1 children with impoverished language delivered by trained education practitioners in schools. Children receiving the language intervention were compared to a matched comparison group not receiving the intervention. Baselines of receptive and expressive language ability were taken pre-intervention and post-intervention using standardized language assessments. The intervention consisted of eight sessions delivered over eight weeks by trained education practitioners. The children in the intervention group made significant gains in their expressive language compared to the comparison group in the length and complexity of their utterances. Neither the intervention group nor the comparison group made any gains in their receptive language. This effectiveness study showed that small-group language intervention for children with impoverished language delivered by trained education practitioners in schools is effective in facilitating children's expressive language. It is proposed that education practitioners would benefit from more knowledge of children's speech, language and communication development and training in how to assess and measure these skills in young children appropriately in a school context. (Contains 4 tables.)