This study investigates the effects of a thinking skills approach on the on task rates of pupils with Special Educational Needs (SEN). There were three situations: two experimental and one controlled. The experimental situations compared on task rates of 19 primary-aged pupils with SEN in thinking skills (TS) and non-thinking skills (XTS) lessons. These same 19 pupils' on task rates were then compared to the 19 different pupils with SEN in the control situation (CON). The study found that pupils with SEN had significantly higher on task rates in thinking skills lessons compared to the non-thinking skills lessons and pupils with SEN in the control situation. This study also found that pupils' on task rate was directly proportional to the level of thinking skills content in a lesson. In addition it was found that pupils in thinking skills lessons spent significantly more time working collaboratively.