This paper attempts to show that the relationship between current theoretical understanding of the origin and acquisition of language and the process of second language classroom instruction requires a basis in empirical research. Areas in which this research is needed include the importance of the teacher, especially in relation to "teacher talk," language proficiency, views of learning and teaching, and expectations of their students; classroom processes, including the use of first and second languages, simplification and repair strategies, and the relative commitment to receptive versus productive language use; and the learner's role, including students' views on learning, and developmental or process-product aspects of learning. (MSE)