A review of research demonstrates that both oral and written language continue to develop through adulthood. Studies show that such skills as the abilities to interpret metacognitive verbs, to make word associations, and to understand syntax improve with age. Adolescents and adults use language that solidifies them with their peer group. Adolescents use emotive, connotative, and socially coded language. Their socially coded language of swearing shows how conscious they are of how they are perceived linguistically. Furthermore, they are very much aware of linguistic structures appropriate to gender. In writing, semantic and syntactic complexity, complex audience awareness, and skill in narration are indicators of maturity. Writing improves when freed from the level of transmitting information, and is stimulated by interaction and conversation. Student-centered, concept-based transactional learning fosters learning in the classroom. Adolescent language development can be achieved by: (1) student initiative; (2) incorporation of prior knowledge; (3) inclusion of the learner's cultural context; and (4) interaction between school and society. Despite favorable research, contemporary U.S. high schools rarely employ language oriented, collaborative problem solving. Teachers need to learn how to implement such strategies, and they must have the support of administrators, the community, and the government in incorporating language-based instructional methods into the curriculum. (Fifty-four references are attached.) (SG)