The state of the art of research in second language acquisition is reviewed. A framework is first established for the examination of second language learning. The concept of proficiency is addressed with respect to its theoretical basis, rating scales, formal tests, and interlanguage studies. The social context of second language acquisition is examined with attention to social dominance patterns, preservation, and adaptation. The role of individual learner factors (affective and cognitive, personality, and age) as it has been brought to light by research is reviewed. Of pedagogical importance is a discussion on learning conditions, natural vs. classroom learning, and varieties of classroom approaches, including immersion. The dilemma of identifying the language learning process is seen from the theoretical viewpoint and from the viewpoint of such research themes as the first language-second language connection, the explicit-implicit option, the code-communication dilemma, and the developmental question. A number of empirical studies are reviewed, and directions for future research are suggested. (JB)