According to the Ethnologue, Kiowa (kio) had 400 speakers as of 2007. According to “Modina Waters using children’s story book to keep Kiowa language alive,” there are only 100 fluent Kiowa speakers, and Modina Waters has created a bilingual book for children.
To promote language use, they have a language nest initiative, where people are encouraged to speak Kiowa at home. The Kiowa Kids Language Resource Page includes links to three different dictionaries, a list of words useful for the home, and large-font vocabulary to cut out and use as labels in the home. (Note that the Kiowa Dictionary says that it “is the exclusive domain of Kiowa families.”)