[4] The similarities between Atakapa and Chitimacha, at least, may be attributable to periods of "intense contact [between speakers of the two languages] owing to their geographic proximity.

[7] The speakers interviewed by Duralde lived in the easternmost part of Atakapa territory, around Poste des Attakapas (now Saint Martinville).

In 1885, Albert Gatschet collected words, sentences, and texts from two native Atakapa speakers, Louison Huntington and Delilah Moss[8] at Lake Charles, Louisiana.

John R. Swanton worked with another two speakers near Lake Charles: Teet Verdine in 1907, and Armojean Reon in 1908.

[6] John Swanton argued that the Béranger vocabulary represented the Akokisa language, spoken by a people who lived somewhat inland from Galveston Bay.

Swadesh further notes that /m/ often surfaces as [n] or [ŋ] word-finally in some adjectives, but "irregular variations in [Gatschet's] writing" preclude him from settling on any further conditions for this.

[10] Additionally, it is unclear whether /n/ is indeed a distinct phoneme from /ŋ/; if this is the case, argues Swadesh, then words containing final /n/ must have arrived in a later period.

Consonant clusters consisting of a stop followed by a sibilant — themselves arising from vowel epenthesis — are generally contracted to /c/.

This meaning that the language stacks (primarily within the verbal complex) a number of affixes to express locatives, tense, aspect, modality, valency adjustment, and person/number (as both subject and object), which are assembled in a rather specific order.

[11] The language is largely head-marking; however, reduplication of an adjectival stem tends to show dependent-marking, as it often expresses the plurality of the noun it describes.

[11] Additionally, there is no mention of the assertive suffix -š in Swanton's work; Kaufman (2014) derives it by analogizing Atakapa and Chitimacha.