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").
Semitic, Berber, Egyptian, and Cushitic had been generally accepted as members of a "Hamito-Semitic" family, while Chadic, Fulani, "Nilo-Hamitic", and Hottentot had all been controversially proposed as members. 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. This demonstration also led to the rejection (by him and by linguistics as a whole) of the term Hamitic as having no coherent meaning in historical linguistics; as a result, he renamed the newly reclassified family "Afroasiatic".
Following Schapera and rejecting Meinhof, he classified Hottentot as a member of the Central Khoisan languages. To Khoisan he also added the much more northerly Hadza (Hatsa) and Sandawe.
His most revolutionary step was the postulation of the Nilo-Saharan family. This is still controversial, because so far attempts to reconstruct this family have been unsuccessful, but it holds promise and is it widely used. Prior linguists had noticed an apparent relationship between the majority of the languages, but had never formally proposed a family. These languages – the Eastern Sudanic, Central Sudanic, Kunama, and Berta branches – Greenberg placed into a core group he called Chari–Nile, to which he added all the remaining unclassified languages of Africa that did not have noun classes. The distinction between Chari–Nile and the peripheral branches has since been abandoned. On a lower level, he placed "Nilo-Hamitic" firmly within Nilotic, following a suggestion of Köhler, and placed Eastern Sudanic on a firmer foundation.
Finally, he assigned the unclassified languages of the Nuba Hills of Kordofan to the Niger–Congo family, calling the result Congo–Kordofanian. The relationship has been accepted, with the exception of the "Tumtum" group, though the Kordofanian languages are no longer seen as being a primary branch, and the name 'Congo–Kordofanian' is no longer used.
Greenberg's four families became the dominant conception of African languages, though his subclassification did not fare as well. Niger−Congo and Afroasiatic are nearly universally accepted, with no significant support for Hamitic or the independence of Bantu. Nilo-Saharan is still considered provisional. Khoisan is now rejected by specialists, except as a term of convenience, though it may be retained in less specialized literature.
The book classifies Africa's languages into four stocks not presumed to be related to each other, as follows:
I.A Niger–Congo
I.A.1 West Atlantic
I.A.1.a Northern: Wolof, Serer-Sin, Fulani, Serer-Non, Konyagi, Basari, Biafada, Badyara (Pajade), Dyola, Mandyak, Balante, Banyun, Nalu, Cobiana, Cassanga, Bidyogo
I.A.1.b Southern: Temne, Baga, Landoma, Kissi, Bulom, Limba, Gola
I.A.2 Mande
I.A.2.a Western
I.A.2.a.1 Malinke, Bambara, Dyula, Mandinka, Numu, Ligbi, Huela, Vai, Kono, Koranko, Khasonke Bobo
I.A.2.a.3 Mende, Loko, Gbandi, Loma, Kpelle (Guerze)
I.A.2.a.4 Susu, Dyalonke
I.A.2.a.5 Soninke, Bozo
I.A.2.a.6 Duun, Dzuun, Jo, Seenku (Sembla), Kpan, Banka
I.A.2.b Eastern
I.A.2.b.1 Mano, Dan (Gio), Guro (Kweni), Mwa, Nwa, Beng, Gban, Tura (Wen), Yaure
I.A.2.b.2 Samo, Bisa, Busa, Kyenga, Shanga
I.A.3 Voltaic
I.A.3.a Senoufo: Minianka, Tagba, Foro, Tagwana (Takponin), Dyimini, Nafana
I.A.3.b.
Lobi-Dogon: Lobi, Dyan, Puguli, Gan, Gouin, Turuka, Doghosie, Doghosie-Fing, Kyan, Tara, Bwamu, Wara, Natioro,
Dogon, Kulango
I.A.3.c Grusi: Awuna, Kasena, Nunuma, Lyele, Tamprusi,
Kanjaga (Bulea) (moved to group d), Degha, Siti, Kurumba (Fulse), Sisala
I.A.3.d Mossi, Dagomba, Kusasi, Nankanse, Talensi, Mamprusi, Wala, Dagari, Birifo, Namnam, Kanjaga (Bulea) (moved from group c)
I.A.3.e Tem, Kabre, Delo, Chala
I.A.3.f Bargu (Bariba)
I.A.3.g Gurma, Tobote (Basari), Kasele (Chamba), Moba
I.A.3.x Dogon
I.A.4 Kwa
I.A.4.a Kru: Bete, Bakwe, Grebo, Bassa, De, Kru (Krawi)
I.A.4.b Avatime, Nyangbo, Tafi, Logba, Likpe, Ahlo, Akposo, Lefana, Bowili, Akpafu, Santrokofi, Adele, Kebu, Anyimere, Ewe, Aladian, Avikam, Gwa, Kyama, Akye, Ari, Abe, Adyukru, Akan (Twi, Anyi, Baule, Guang, Metyibo, Abure), Ga, Adangme
I.A.4.c Yoruba, Igala
I.A.4.d Nupe, Gbari, Igbira, Gade
I.A.4.e Bini, Ishan, Kukuruku, Sobo
I.A.4.f Idoma, Agatu, Iyala
I.A.4.g Ibo
I.A.4.h Ijo
I.A.5 Benue–Congo
I.A.5.A Plateau
I.A.5.A.1
I.A.5.A.1.a Kambari, Dukawa, Dakakari, Basa, Kamuku, Reshe
I.A.5.A.1.b Piti, Janji, Kurama, Chawai, Anaguta, Buji, Amap, Gure, Kahugu, Ribina, Butawa, Kudawa
I.A.5.A.2 Afusare, Irigwe, Katab, Kagoro, Kaje, Kachicheri, Morwa, Jaba, Kamantan, Kadara, Koro, Afo
I.A.5.A.3 Birom, Ganawuri (Aten)
I.A.5.A.4 Rukuba, Ninzam, Ayu, Mada, Kaninkwom
I.A.5.A.5 Eggon, Nungu, Yeskwa
I.A.5.A.6 Kaleri, Pyem, Pai
I.A.5.A.7 Yergam, Basherawa
I.A.5.B Jukunoid: Jukun, Kentu, Nyidu, Tigong, Eregba, Mbembe, Zumper (Kutev, Mbarike), Boritsu
I.A.5.C Cross-River
I.A.5.C.1 Boki, Gayi (Uge), Yakoro
I.A.5.C.2 Ibibio, Efik, Ogoni (Kana), Andoni, Akoiyang, Ododop, Korop
I.A.5.C.3 Akunakuna, Abine, Yako, Asiga, Ekuri, Ukelle, Okpoto-Mteze, Olulomo
I.A.5.D Bantoid: Tiv, Bitare, Batu, Ndoro, Mambila, Bute, Bantu
I.A.6 Adamawa–Eastern
I.A.6.A Adamawa
I.A.6.A.1 Tula, Dadiya, Waja, Cham, Kamu
I.A.6.A.2 Chamba, Donga, Lekon, Wom, Mumbake
I.A.6.A.3 Daka, Taram
I.A.6.A.4 Vere, Namshi, Kolbila, Pape, Sari, Sewe, Woko, Kotopo, Kutin, Durru
I.A.6.A.5 Mumuye, Kumba, Gengle, Teme, Waka, Yendang, Zinna
I.A.6.A.6 Dama, Mono, Mbere, Mundang, Yasing, Mangbei, Mbum, Kpere, Lakka, Dek
I.A.6.A.7 Yungur, Mboi, Libo, Roba
I.A.6.A.8 Kam
I.A.6.A.9 Jen, Munga
I.A.6.A.10 Longuda
I.A.6.A.11 Fali
I.A.6.A.12 Nimbari
I.A.6.A.13 Bua, Nielim, Koke
I.A.6.A.14 Masa
I.A.6.B Eastern
I.A.6.B.1 Gbaya, Manja, Mbaka
I.A.6.B.2 Banda
I.A.6.B.3 Ngbandi, Sango, Yakoma
I.A.6.B.4 Zande, Nzakara, Barambo, Pambia
I.A.6.B.5 Bwaka, Monjombo, Gbanziri, Mundu, Mayogo, Bangba
I.A.6.B.6 Ndogo, Bai, Bviri, Golo, Sere, Tagbo, Feroge, Indri, Mangaya, Togoyo
I.A.6.B.7 Amadi (Madyo, Ma)
I.A.6.B.8 Mondunga, Mba (Bamanga)
I.B Kordofanian
I.B.1 Koalib: Koalib, Kanderma, Heiban, Laro, Otoro, Kawama, Shwai, Tira, Moro, Fungor
I.B.2 Tegali: Tegali, Rashad, Tagoi, Tumale
I.B.3 Talodi: Talodi, Lafofa, Eliri, Masakin, Tacho, Lumun, El Amira
I.B.4 Tumtum: Tumtum, Tuleshi, Keiga, Karondi, Krongo, Miri, Kadugli, Katcha
I.B.5 Katla: Katla, Tima
II.A Songhai
II.B Saharan
II.B.a Kanuri, Kanembu
II.B.b Teda, Daza
II.B.c Zaghawa, Berti
II.C Maban: Maba, Runga, Mimi of Nachtigal, Mimi of Gaudefroy-Demombynes
II.D. Fur
II.E. Chari–Nile
II.E.1 Eastern Sudanic
II.E.1.1 Nubian
II.E.1.1.a Nile Nubian (Mahas-Fadidja and Kenuzi-Dongola)
II.E.1.1.b Kordofanian Nubian: Dair, Dilling, Gulfan, Garko, Kadero, Kundugr
II.E.1.1.c Midob
II.E.1.1.d Birked
II.E.1.2 Murle (Beir), Longarim, Didinga, Suri, Mekan, Murzu, Surma (including Tirma and Zulmanu), Masongo
II.E.1.3 Barea
II.E.1.4 Ingassana (Tabi)
II.E.1.5 Nyima, Afitti
II.E.1.6 Temein, Teis-um-Danab
II.E.1.7 Merarit, Tama, Sungor
II.E.1.8 Dagu of Darfur, Baygo, Sila, Dagu of Dar Dagu (Wadai), Dagu of Western Kordofan, Njalgulgule, Shatt, Liguri
II.E.1.9 Nilotic
II.E.1.9.a Western
II.E.1.9.a.1 Burun
II.E.1.9.a.2 Shilluk, Anuak, Acholi, Lango, Alur, Luo, Jur, Bor
II.E.1.9.a.3 Dinka, Nuer
II.E.1.9.b Eastern
II.E.1.9.b.1 Bari, Fajulu, Kakwa, Mondari
II.E.1.9.b.2a Jie, Dodoth, Karamojong, Teso, Topotha, Turkana
II.E.1.9.b.2b Masai
II.E.1.9.b.3 Southern: Nandi, Suk, Tatoga
II.E.1.10 Nyangiya, Teuso
II.E.2 Central Sudanic
II.E.2.1 Bongo, Baka, Morokodo, Beli, Gberi, Sara dialects (Madjinngay, Gulai, Mbai, Gamba, Kaba, Dendje, Laka), Vale, Nduka, Tana, Horo, Bagirmi, Kuka, Kenga, Disa, Bubalia
II.E.2.2 Kreish
II.E.2.3 Binga, Yulu, Kara [= Tar Gula]
II.E.2.4 Moru, Avukaya, Logo, Keliko, Lugbara, Madi
II.E.2.5 Mangbetu, Lombi, Popoi, Makere, Meje, Asua
II.E.2.6 Mangbutu, Mamvu, Lese, Mvuba, Efe
II.E.2.7 Lendu
II.E.3 Berta
II.E.4 Kunama
II.F Koman/Coman: Komo, Ganza, Uduk, Gule, Gumuz, Mao
III.A Semitic
III.B Egyptian
III.C Berber
III.D Cushitic
III.D.1 Northern Cushitic: Beja (Bedauye)
III.D.2 Central Cushitic: Bogo (Bilin), Kamir, Khamta, Awiya, Damot, Kemant, Kayla, Quara
III.D.3 Eastern Cushitic: Saho-Afar, Somali, Galla, Konso, Geleba, Marille, (Reshiat, Arbore), Gardula, Gidole, Gowaze, Burji, Sidamo, Darasa, Kambata, Alaba, Hadya, Tambaro, Mogogodo (added 1966)
III.D.4 Western Cushitic: Janjero, Wolamo, Zala, Gofa, Basketo, Baditu, Haruro, Zaysse, Chara, Gimira, Benesho, Nao, Kaba, Shako, She, Maji, Kafa, Garo, Mocha, Anfillo (Mao), Shinasha, Bako, Amar, Bana, Dime, Gayi, Kerre, Tsamai, Doko, Dollo
III.D.5 Southern Cushitic: Burungi (Mbulungu), Goroa (Fiome), Alawa (Uwassi), Iraqw, Mbugu, Sanye [= Dahalo], Ngomvia (added 1966)
III.E Chad
III.E.1
III.E.1.a Hausa, Gwandara
III.E.1.b Ngizim, Mober [= Kanuri, not Chadic], Auyokawa, Shirawa, Bede
III.E.1.c
III.E.1.c.i Warjawa, Afawa, Diryawa, Miyawa, Sirawa
III.E.1.c.ii Gezawa, Seiyawa, Barawa of Dass
III.E.1.d
III.E.1.d.i Bolewa, Karekare, Ngamo, Gerawa, Gerumawa, Kirifawa, Dera (Kanakuru), Tangale, Pia, Pero, Chongee, Maha (added 1966)
III.E.1.d.ii Angas, Ankwe, Bwol, Chip, Dimuk, Goram, Jorto, Kwolla, Miriam, Montol, Sura, Tal, Gerka
III.E.1.d.iii Ron
III.E.2 Kotoko group: Logone, Ngala [= Mpade?], Buduma, Kuri, Gulfei, Affade, Shoe, Kuseri
III.E.3 Bata–Margi group
III.E.3.a Bachama, Demsa, Gudo, Malabu, Njei (Kobochi, Nzangi, Zany), Zumu (Jimo), Holma, Kapsiki, Baza, Hiji, Gude (Cheke), Fali of Mubi, Fali of Kiria, Fali of Jilbu, Margi, Chibak, Kilba, Sukur, Vizik, Vemgo, Woga, Tur, Bura, Pabir, Podokwo
III.E.3.b Gabin, Hona, Tera, Jera, Hinna (Hina)
III.E.4
III.E.4.a Hina, Daba, Musgoi, Gauar
III.E.4.b Gisiga, Balda, Muturua, Mofu, Matakam
III.E.5 Gidder
III.E.6 Mandara, Gamergu
III.E.7 Musgu
III.E.8 Bana, Banana (Masa), Lame, Kulung
III.E.9
III.E.9.a Somrai, Tumak, Ndam, Miltu, Sarwa, Gulei [= Tumak?]
III.E.9.b Gabere, Chiri, Dormo, Nangire
III.E.9.c Sokoro (Bedanga), Barein
III.E.9.d Modgel
III.E.9.e Tuburi
III.E.9.f Mubi, Karbo, (added 1966: Jegu, Jonkor, Wadai-Birgid)
IV.A South African Khoisan
IV.A.1 Northern South African Khoisan
IV.A.2 Central South African Khoisan
IV.A.3 Southern South African Khoisan
IV.B Sandawe
IV.C Hatsa
