Raven Coloured Matrices (Raven, Court & Raven, 1998), are often used to assess non-verbal intelligence and reasoning. Performance is evaluated on the basis of the number of correct answers, but growing interest is paid to error analysis. The goal of the present study is to better analyze the types of errors in Coloured Matrices comparing performance of Down syndrome individuals with that of typically developing individuals matched for mental age. Results show a different pattern of errors in the two groups, although global performance is comparable. These findings are discussed considering cognitive processes involved in solving problems proposed by Coloured Matrices.