The Kalenjin languages form a cluster of closely related Southern Nilotic languages spoken across the Rift Valley region of Kenya. The name "Kalenjin" was adopted as a collective identity in the mid-twentieth century to unite a group of peoples sharing common linguistic ancestry, cultural practices, and the kok age-set initiation system.

The Kalenjin cluster comprises a number of distinct but mutually intelligible or closely related language varieties, the principal ones being:

• Kipsigis — the largest variety by speaker population, centred in Bomet and Kericho counties
• Nandi — spoken in Nandi County and the wider Uasin Gishu plateau
• Tugen — spoken in Baringo County
• Keiyo (Elgeyo) — spoken in Elgeyo-Marakwet County
• Marakwet — spoken in the Elgeyo-Marakwet highlands
• Pokot (Pökoot) — spoken in West Pokot and Baringo counties, and into Uganda
• Sabaot — spoken on Mount Elgon, straddling the Kenya-Uganda border
• Terik — a smaller variety spoken in Nandi County
• Okiek (Ogiek) — spoken by the forest-dwelling Ogiek communities of the Mau and Mount Kenya forests
• Akie — spoken by a small hunter-gatherer community in northern Tanzania

Linguists classify several of these varieties as distinct languages rather than dialects of a single language, and the internal boundaries of the cluster remain a matter of ongoing scholarly discussion. The degree of mutual intelligibility varies considerably across the cluster: Nandi and Kipsigis are closely related, while Pokot and Sabaot occupy more peripheral positions within the grouping. The Ogiek varieties in particular represent languages of significant documentary urgency, spoken by small and mobile forest communities whose languages have received limited formal documentation.

This archive does not impose a single dialect or variety structure on deposits. The Kalenjin Languages Archive is organised as a unified collection for the cluster as a whole, reflecting the reality that variety affiliation can be fluid, that many speakers identify primarily as "Kalenjin" rather than with a specific sub-variety, and that comparative and cross-variety research is a primary use case for this collection. Geographic provenance, speaker variety affiliation, and language variety codes are recorded at the item level, allowing researchers to filter and compare across the cluster without the archive having pre-committed to a fixed internal taxonomy.

Materials collected include oral histories, kok initiation songs and poetry, pastoral knowledge, proverbs, folktales, and contemporary speech across registers. The Kalenjin oral tradition — including its elaborate systems of age-set poetry, cattle praise, and riddle traditions — is of considerable importance to East African oral literature scholarship.