This article describes how a behaviour contract has been implemented to achieve positive and enduring results for four boys with a diagnosis of an autistic spectrum disorder (ASD). Four case studies are described which address reductions in behaviours such as assaultive and destructive behaviour, out-of-seat behaviour, inappropriate contact with others and loud vocalisations, while also increasing the following of directions in the classroom and at playtimes. The common thread across all of the case studies is the use of the behaviour contract and the link that is built between home and school. The authors suggest that it is this contingent link that is the basis for the success in each of these studies. Based on their research, they believe that the behaviour contract can be considered an important and useful tool in helping address challenging behaviours in children with an ASD. Emma Hawkins is the Director of Education at The Jigsaw CABAS® School and oversees the implementation of strategies at the school to improve the behaviour of the pupils. Grant Gautreaux, from Nicholls State University in Louisiana, consults at The Jigsaw CABAS® School and is a member of the CABAS® Board. All of the remaining authors work at The Jigsaw CABAS® School and have successfully implemented the behaviour contract in their classrooms.