 Research comparing the academic achievement made by native speakers of English and native speakers of Spanish illustrates that while both groups show growth in their native and secondary language, English native speakers are more dominant in their primary language, but Spanish native speakers are able to achieve a more balanced form of bilingualism, that is, relatively equal in their ability to communicate orally and in writing in their primary and secondary language (Howard et al.2003, p. 36).The evidence of the effectiveness of TWI is consistent in programs where less common languages are maintained as well.