t is estimated that more than half of the world’s population\r\nuses two or more languages in their everyday life, but it remains\r\ndifficult to know the exact number of people who speak more\r\nthan one language. What can be said is that bilingualism is\r\nnot a rare phenomenon; it occurs in all countries in the world,\r\nin all social classes and in all age groups\r\n1\r\n. In Spain, six out of\r\nthe sixteen autonomous communities have other co-official\r\nlanguages in addition to Castilian, and many of the residents of\r\nthese communities are bilingual in the corresponding languages.\r\nAt the same time, according to Eurostat\r\n2\r\n, Spain is one of the\r\ncountries in the European Union with the highest percentage of\r\nadults who do not speak any foreign language.\r\nIn order to improve this situation, one of the main\r\ncommitments of the Ministry of Education and Science (MEC)\r\nhas been the introduction of bilingual education in all stages of\r\ncompulsory education as well as in the second cycle of early\r\nyears education (ages 3-5).