The most commonly used dialects are Hasinai and Hainai; others include Kadohadacho, Natchitoches and Yatasi.

Kitsai and Wichita are now extinct, and Pawnee and Arikara each have fewer surviving speakers than Caddo does.

The Kiwat Hasí꞉nay ('Caddo Home') foundation, located at the tribal home of Binger, Oklahoma, offers regular Caddo language classes, in addition to creating dictionaries, phrase books, and other Caddo language resources.

They have also made a long-term project of trying to record and digitally archive Caddoan oral traditions, which are an important part of Caddo culture.

In general, the long vowels do not feature this kind of variation but are simply lengthened versions of the phonemes that are represented in the chart.

[14] Caddo also has four diphthongs, which can be written a number of different ways; the transcription below shows the typical Caddo Nation orthography (a vowel paired with a glide) and the IPA version, represented with vowels and offglides.

Tone occurs both lexically (as a property of the word), non-lexically (as a result of tonological processes), and also as a marker of certain morphological features.

At the present stage of research, the processes seem to be unrelated, but they represent a phonetic reduction in consonant clusters; therefore, they are listed below without much further explanation.