In the Basque Autonomous Community, two languages have been spoken for centuries, Spanish and Euskera or Basque. Basque, unlike the rest of modern Spanish languages, does not come from Latin nor does it belong to the Indo-European family.

Spanish and Basque are co-official in all territories of the autonomous community. The Basque-speaking areas in the modern-day autonomous community are set against the wider context of the Basque language, spoken to the east in Navarre and the French Basque Country. The whole Basque-speaking territory has experienced both decline and expansion in its history. The Basque language experienced a gradual territorial contraction throughout the last nine centuries, and important changes in its sociolinguistic situation in the 20th century for several reasons, including heavy immigration from other parts of Spain, lack of official interest in the promotion of the language, the virtual nonexistence of Basque-language schooling, and some national policies implemented by the different Spanish régimes in the 20th century (see Language policies of Francoist Spain). After the advent of the Statute of Autonomy of the Basque Country in 1982 following Franco’s death, this reductive trend was gradually reversed thanks to the Basque-language schools and the new education system. Basque has always had a strong presence in most of Gipuzkoa, central and eastern Biscay and the northern edge of Álava, while most Basque speakers in western Biscay and the rest of Álava are second-language speakers.

The 2006 sociolinguistic survey of all Basque provinces showed that in 2006 of all people aged 16 and above in the Basque Autonomous Community, 30.1% were fluent Basque speakers, 18.3% passive speakers and 51.5% did not speak Basque. The percentage of Basque speakers was highest in Gipuzkoa (49.1% speakers) and lowest in Álava (14.2%). These results represent an increase on previous years (29.5% in 2001, 27.7% in 1996 and 24.1% in 1991). The highest percentage of speakers was now be found in the 16-24 age range (57.5%), while only 25.0% of those 65 and older reported speaking Basque.

Ten years later, the sociolinguistic survey showed that in 2016 of all people aged 16 and above in the Basque Autonomous Community, 33.9% were fluent Basque speakers, 19.1% passive speakers and 47% did not speak Basque. The proportion of Basque speakers was again highest in Gipuzkoa (50.6%) and lowest in Álava (19.2%).