Several screening instruments for ASD in young children were developed during the last decades. Only few studies compare the discriminative power of these instruments in the same sample. In particular comparisons of instruments that use different informants are scarce in young children. The current study compared the discriminant ability of the Checklist for Early Signs of Developmental Disorders (CESDD) filled out by child care workers with that of frequently used parent questionnaires in a sample of 357 children between 5.57 and 48.13 months old who showed signs of ASD or language delay. The discriminant power of the CESDD was as good as that of parent questionnaires. Therefore, inclusion of child care workers in the early detection of ASD seems promising.