Interlingua is an international auxiliary language (IAL) developed between 1937 and 1951 by the American International Auxiliary Language Association (IALA). It is a constructed language of the "naturalistic" variety, whose vocabulary, grammar, and other characteristics are derived from natural languages. Interlingua proponents maintain that (written) Interlingua is comprehensible to the over 900 million native speakers of Romance languages, though it is actively spoken by only a few hundred.