Tool	Screening age	Resource
CAST	4 to 11 years	http://www.autismresearchcentre.com/tests/cast_test.asp
CHAT	18 to ≥ 24 months	http://www.autismresearchcentre.com/tests/chat_test.asp
CHAT (Denver modifications)	18 to ≥ 24 months	Scambler D, Rogers SJ, Wehner EA. Can the checklist for autism in toddlers differentiate young children with autism from those with developmental delays? J Am Acad Child Adolesc Psychiatry. 2001;40(12):1457–1463.
CHAT-23	16 to 86 months	Wong V, Hui LH, Lee WC, et al. A modified screening tool for autism (Checklist for Autism in Toddlers [CHAT-23]) for Chinese children. Pediatrics. 2004;114(2):e166–e176.
M-CHAT	16 to 48 months	Test: http://www.dbpeds.org/media/mchat.pdf Scoring: http://www.firstsigns.org/screening/tools/rec.htm
PDDST-II	18 to 48 months	http://pearsonassess.com/haiweb/cultures/en-us/productdetail.htm?pid=076-1635-106