Children with Down syndrome often display speech-comprehensibility and grammatical deficits beyond what would be predicted based upon general mental age. Historically, speech-comprehensibility has often been treated using traditional articulation therapy and oral-motor training so there may be little or no coordination of grammatical and speech-comprehensibility treatment. The purpose of this paper is to provide the rationale for and preliminary evidence in support of integrating speech and grammatical intervention using a type of recast treatment in six children with Down syndrome. Speech-comprehensibility and MLU growth in generalisation sessions occurred in 4/6 and 5/6 participants, respectively. Using multiple baseline design logic, two of these participants showed evidence of treatment effects on speech-comprehensibility and two in MLU in generalisation sessions, respectively. The study constitutes a conservative test of the intervention effects for reasons that are discussed. The theoretical and applied significance of these findings are discussed. (Contains 4 figures.)