Languages of Catalonia
The main cause of Spanish and Catalan social bilingualism in modern Catalonia was large-scale migration from the rest of Spain during the 20th century, as Catalonia started a significant industrialization which demanded an increased workforce from elsewhere. Spanish has historically been spoken among a minority of civil servants born in other regions in Spain and among segments of the wealthiest bourgeoisie. Spanish has also been spoken as a second language by most Catalans, as it has been the only official language over long periods since the eighteenth century.
Caló language
Caló (; ; ; ) is a language spoken by the Spanish and Portuguese Romani. It is a mixed language (referred to as a Para-Romani language in Romani linguistics) based on Romance grammar, with an adstratum of Romani lexical items through language shift by the Romani community. It is often used as an argot, a secret language for discreet communication amongst Iberian Romani. Catalan, Galician, Portuguese, and Spanish are closely related varieties that share a common root.