The validity of the calibrated severity scores on the ADOS as reported by Gotham et al. (J Autism Dev Disord 39: 693–705, 2009), was investigated in an independent sample of 1248 Dutch children with 1455 ADOS administrations (modules 1, 2 and 3). The greater comparability between ADOS administrations at different times, ages and in different modules, as reached by Gotham et al. with the calibrated severity measures, seems to be corroborated by the current study for module 1 and to a lesser extent for module 3. For module 2, the calibrated severity scores need to be further investigated within a sample that resembles Gotham’s sample in age and level of verbal functioning.