ALTHOUGH THE LINGUISTS, PSYCHOLOGISTS, AND TEACHERS WHO HAVE STRESSED THE HABITUAL ASPECTS OF LANGUAGE HAVE MADE MANY USEFUL CONTRIBUTIONS TO LINGUISTIC RESEARCH AND LANGUAGE TEACHING, THERE STILL REMAIN SOME BASIC PROBLEMS. WITH THE PSYCHOLOGIST, PEDAGOGUE, SOCIOLOGIST, AND ANTHROPOLOGIST, THE LINGUIST MUST ATTACK THE GROUP OF PROBLEMS ASSOCIATED WITH THE MOTIVATIONAL AND PERSONALITY VARIABLES IN SECOND LANGUAGE LEARNING. MORE AMENABLE TO INVESTIGATION BY LINGUISTS ARE THE PROBLEMS RELATED TO LANGUAGE DESCRIPTION AND CONTRAST. RECENT DEVELOPMENTS IN GRAMMATICAL THEORY HAVE THE POTENTIAL OF CLARIFYING BOTH THE DEEP AND SURFACE STRUCTURES OF LANGUAGE, BUT, TO DATE, THERE IS ONLY A VAGUE AWARENESS OF HOW TO INCORPORATE BOTH ELEMENTS EFFECTIVELY IN COURSE MATERIALS. AN UNDERSTANDING OF LANGUAGE PRODUCTIVITY AND COMPETENCE MIGHT GIVE INSIGHT INTO WHAT ACTUALLY IS INVOLVED IN ANALOGY, GENERALIZATION, AND NUCLEATION. PERHAPS TRANSFORMATIONAL GRAMMAR MIGHT PROVIDE THE ANSWER TO A FRESH APPROACH IN THE GRADATION AND PRODUCTIVITY OF MATERIALS DESIGNED TO TEACH LANGUAGE LEARNERS TO HAVE A NATIVE-LIKE CONTROL OF THE STRUCTURAL ELEMENTS OF THE TARGET LANGUAGE. THIS ARTICLE APPEARED IN "LANGUAGE LEARNING," VOLUME 17, NUMBERS 1-2, JULY 1967, PAGES 21-26. (AB)