The American Academy of Pediatrics recommends Autism Spectrum Disorder (ASD) screening at 18 and 24 months. However, utility of rescreening at 24 months, after a negative 18-month screening, remains unknown. We identified cases of ASD detected at 24 months after a negative 18-month screening (i.e., Catch-24 group; n = 10) and compared them to toddlers detected by 18-month screening (i.e., Early Diagnosis group; n = 203). Repeated ASD-specific screening at 24 months detected children who were missed at their 18-month screening. Thus, our findings support repeated screening for ASD at both 18 and 24 months in order to maximize identification of toddlers with ASD and other neurodevelopmental disorders who require intervention.