It is an expanded and extensively revised version of his 1955 work Studies in African Linguistic Classification, which was itself a compilation of eight articles which Greenberg had published in the Southwestern Journal of Anthropology between 1949 and 1954.

1; however, its second edition of 1966, in which it was published (by Indiana University, Bloomington: Mouton & Co., The Hague) as an independent work, is more commonly cited.

[citation needed] Its author describes it as based on three fundamentals of method: Greenberg's Niger–Congo family was substantially foreshadowed by Westermann's "Western Sudanic", but he changed the subclassification, including Fulani (as West Atlantic) and the newly postulated Adamawa–Eastern, excluding Songhai, and classifying Bantu as merely a subfamily of Benue–Congo (previously termed "Semi-Bantu").

He accepted Chadic (while changing its membership), and rejected the other three, establishing to most linguists' satisfaction that they had been classified as "Hamitic" for purely typological reasons.

Finally, he assigned the unclassified languages of the Nuba Hills of South Kordofan to the Niger–Congo family, calling the result Congo–Kordofanian.