This document discusses theories of first and second language acquisition. It begins by distinguishing between acquisition, which is subconscious, and learning, which is conscious knowledge of rules. It then covers three theories of first language acquisition: behaviorism, nativism, and functionalism. Issues in first language acquisition discussed include competence vs performance, comprehension vs production, nature vs nurture, universals, and the role of input, imitation, practice, and discourse. The document concludes by outlining Krashen's five hypotheses of second language acquisition, including the acquisition-learning distinction and the role of comprehensible input.