Several instruments have been developed to screen for autism spectrum disorders (ASD) in high-risk populations. However, few studies compare different instruments in one sample. Data were gathered from the Early Screening of Autistic Traits Questionnaire, Social Communication Questionnaire, Communication and Symbolic Behavior Scales-Developmental Profile, Infant-Toddler Checklist and key items of the Checklist for Autism in Toddlers in 238 children (mean age = 29.6 months, SD = 6.4) at risk for ASD. Discriminative properties are compared in the whole sample and in two age groups separately (8–24 months and 25–44 months). No instrument or individual item shows satisfying power in discriminating ASD from non-ASD, but pros and cons of instruments and items are discussed and directions for future research are proposed.