Parents of three groups of children completed the Children’s Behavior Questionnaire (CBQ). Participants were children with Down syndrome aged 4-11 years (n = 55), prematurely born children aged 5 years (n = 97), and a group of normally developing kindergarten children 5-7 years of age (n = 91). Mean levels and factor structures on the CBQ were compared between the three groups. The children with Down syndrome had less attentional focusing and expressed less inhibitory control and less sadness than the normally developing children. There were also group differences in temperament structures, especially a clearer emotional factor of “surgency” among the children with Down syndrome. The only significant difference in mean temperament scores between the premature children and the control group was that the former evinced less attentional focussing. The temperament structures in the Norwegian samples were very similar to those reported in earlier studies, conducted in China and the US.