Aspects of second language learning and instruction are explored in order to develop a rationale for a comprehension-based approach to language instruction. Eight characteristic pedagogical assumptions are critically examined, including assumptions regarding the role of grammar, age differences in learning ability, the priority given to each of the four language skills, and the relationship between production and reception. Aspects of child second language learning that are relevant to older learners are considered, particularly those related to a naturalistic setting for learning. Two programs are reviewed that involve methods of teaching reading and listening comprehension. These methods illustrate the implications of overcoming the productive bias of more formal language instruction. Suggestions are offered for encouraging comprehension and building receptive vocabulary. Only through long exposure to a language can second language learners understand what sounds right and effectively monitor their own speech. Teaching grammar before reception reverses the natural sequence of acquisition. A bibliography is appended. (RW)