Spelling errors are usually studied in dictations, but teachers report that children with school difficulties often make spelling mistakes when they copy a text too. The present study examines the performance on a text copying task and a text dictation task of two groups of children known for their difficulties in spelling, that is, 22 with symptoms of ADHD and 13 with dyslexia, comparing them with matched controls to see whether children with spelling difficulties make more copying task errors than do controls, whether they make fewer mistakes when copying than when writing under dictation, and whether the pattern of errors remains the same or differs in copy and dictation tasks. Our results show that although children with spelling difficulties made fewer errors in the copying task than under dictation, they still made phonological errors and mistakes relating to accents and duplicates. The pattern of errors differed slightly between the children with dyslexia and those with ADHD, presumably as a consequence of their different underlying weaknesses—related mainly to phonology and orthographic representation in the case of dyslexia and to attentional control in the case of ADHD.