Christopher Ehret is professor of African history and African historical linguistics, whose research focuses on linguistic taxonomy and reconstruction with the archeological record. He has published eight books and over seventy scholarly articles on a wide range of historical, linguistic, and anthropological subjects. He has also contributed to a number of encyclopedias on African topics and on world history.
Ehret’s historical books emphasize early African history. In An African Classical Age (1998) he argues for a conception of the period from 1000 BC to 400 AD in East Africa as a "classical age" during which a variety of major technologies and social structures first took shape. His Civilizations of Africa: A History to 1800 (2002), brings together the whole of African history from the close of the last ice age down to the end of the eighteenth century. With the archaeologist Merrick Posnansky, he also edited The Archaeological and Linguistic Reconstruction of African History (1982), at that time a state-of-the-field survey of the correlation of linguistic and archaeological findings in the different major regions of the continent.

His linguistic works include A Comparative Reconstruction of Proto-Nilo-Saharan (2002), Reconstructing Proto-Afroasiatic (1995), and The Historical Reconstruction of Southern Cushitic Phonology and Vocabulary (1980). He has also written monographic articles on Bantu subclassification, on internal reconstruction in Semitic, on the reconstruction of proto-Cushitic and proto-Eastern Cushitic, and, with Mohamed Nuuh Ali, on the classification of the Soomaali languages. These reconstructions have not been well received, and are not followed by other linguists.

In recent years Ehret has carried his work in several new directions. One of these has been the reconstruction of the history and evolution of early human kinship systems. A second interest has been to apply the methods of historical reconstruction from linguistic evidence to issues in anthropological theory and in world history. He has also collaborated with geneticists in seeking to correlate linguistic with genetic findings (e.g., Sarah A. Tishkoff, Floyd A. Reed, F. R. Friedlaender, Christopher Ehret, Alessia Ranciaro, et al., “The Genetic Structure and History of Africans and African Americans,” Science 324, 22 May 2009) and in developing mathematical tools for dating linguistic history (e.g., Andrew Kitchen, Christopher Ehret, Shiferew Assefa, and Connie Mulligan, "Bayesian phylogenetic analysis of Semitic languages identifies an Early Bronze Age origin of Semitic in the Near East," Proceedings of the Royal Society B: Biological Sciences, July 2009).