Behavioural approaches can be used effectively to teach new skills and to change behaviours that are challenging and not socially adaptive. The behaviour modification approach--now called applied behaviour analysis--is based on the assumption that all behaviours are learned, both the useful ones (new skills) and the ones that are not so useful (challenging or difficult behaviours). This article describes two papers from Kathleen Feeley and Emily Jones that demonstrate the strengths of the behavioural approach for children with Down syndrome.