This research was supported by a grant from the Australian Government Department of Social Services and the study was conducted using the infrastructure and resources of the Autism Specific Early Learning and Care Centres (ASLECCs) in Queensland (AEIOU Nathan ASELCC and Gold Coast Centre), Victoria (Margot Prior ASELCC), New South Wales (KU Marcia Burgess ASELCC), Tasmania (St Giles ASELCC), South Australia (Anglicare Daphne Street ASELCC), and Western Australia (Autism Association of Western Australia ASELCC). The ASELCCs were established through funding from the Department of Social Services. David Trembath was supported by a National Health and Medical Research Council ECR Fellowship.