Chumashan is an extinct and revitalizing family of languages that were spoken on the southern California coast by Native American Chumash people, from the Coastal plains and valleys of San Luis Obispo to Malibu, neighboring inland and Transverse Ranges valleys and canyons east to bordering the San Joaquin Valley, to three adjacent Channel Islands: San Miguel, Santa Rosa, and Santa Cruz.

Chumashan, Yukian, and southern Baja languages are spoken in areas with long-established populations of a distinct physical type.

John Peabody Harrington conducted fieldwork on all the above Chumashan languages, but obtained the least data on Island Chumash, Purisimeño, and Obispeño.

The languages are named after the local Franciscan Spanish missions in California where Chumashan speakers were relocated and aggregated between the 1770s and 1830s: Roland Dixon and Alfred L. Kroeber suggested that the Chumashan languages might be related to the neighboring Salinan in a Iskoman grouping.

The distinctive high central vowel is written various ways, including <ɨ> "barred I," <ə> "schwa" and <ï> "I umlaut."

Striking features of this system include The Central Chumash languages have a complex inventory of consonants.