Literature concerning human information processing is examined for its implications and extensions into the realm of input processing during second language learning. It is argued that learners can process input solely for meaning, and that once meaning can be accessed automatically, attention can be directed to certain "non-important" structures in the input. However, it is suggested that affective variables may contribute to the eventual processing of these structures, and that second language learners may pidginize if attention is not directed toward items of lesser communicative value. It is also suggested that the processes involved in the reception and decoding of input help to explain the emergence of form in learner speech. Specific recommendations for approaching the empirical investigation of the role of automatic and controlled processes in input processing are made. (MSE)