The main objective of this study was to assess and compare the adaptive behaviour level of children and adolescents with and without intellectual disability trying to understand how the differences in this area could be influenced by contents and curricula. The sample was composed by 589 children and adolescents with and without intellectual disabilities (both ages 6 to 16, randomly selected from special and regular schools, respectively). The Portuguese version of Adaptive Behaviour Scale was used and administered through an interview, to a proxy who knew the individual being evaluated. Controlling for age, gender, diagnosis, and living area we found that there were statistical significant differences between both groups on most of adaptive behaviour domains in all variables. One of the conclusions is that curricula in special and regular schools differ a lot on contents and in participation activities within the community and that might be one of the causes of the non-skills acquisition by the children and adolescents with intellectual disabilities.