The many dimensions of individual differences that make each learner a challenge to the foreign language teacher are discussed. The teacher must interpret the information and provide differentiated environments to "match" these differences. Emphasis is placed upon learning styles and learning strategies. An historical perspective of adapting instruction to individual differences is presented. Teachers' intuitive adaptations, factors necessary to consider when adapting instruction to student characteristics, and a procedure that might be used to adapt to students' learning styles are discussed. One important dimension of learning style is students' differing needs for varying degrees of structure. Adapting instruction to students' learning style usually includes varying the structure of the environment, the modality of the material, and the sociological setting in order to meet students' needs. Hunt's conceptual level matching model is discussed. The model describes students both in terms of their immediate learning needs and their long-term developmental growth needs so that environments can be adapted to meet these needs. Foreign language teachers, materials developers, and researchers need to understand that it is not the learning task itself but what the student does with the task that determines what is learned. (SW)