In the comprehension approach to second language instruction, the major procedure is to provide students with comprehensible input, which it is the students' responsibility to understand. The aim is to encourage nucleation of the target language, that is the crystallization of the rule system. Teaching procedures focus on strategies for implicit or nonconscious language learning. Speaking is not taught, but is expected to develop as the individual acquires knowledge of the language. The training includes prenucleation, nucleation, and postnucleation stages. The prenucleation stage provides for emotional and intellectual preparation; the nucleation stage provides for comprehension of complex sentences, abstract concepts, and vocabulary; and the postnucleation stage is concerned with the reduction of persistent speaking errors, increasing cultural information and understanding, teaching various writing styles, and teaching specialized vocabulary when needed. An experimental intensive German course taught by this method resulted in high achievement and motivation without explicit instruction in grammar or translation of vocabulary items. It is suggested that comprehension training should continue for 1000 hours to prepare students for literary reading and composition skills. (MSE)