How Long? A Synthesis of Research on Academic Achievement in a Second Language

To expand the current theoretical base in second language acquisition, this article proposes nine generalizations on optimal age, L1 cognitive development, and L2 academic achievement. These generalizations summarize the author's and others' research on second language acquisition for schooling purposes. In this synthesis, relationships among the following variables are considered: first language acquisition, second language acquisition, student age at the time of exposure to a second language, academic achievement (as measured by standardized tests in all subject areas), membership in a language majority or language minority community, and language(s) of instruction in school. The five new generalizations presented at the end of the article, which are based on research on academic achievement in a second language, merit additional research to validate and refine them.