Explicit classroom correction of the second language learner's errors is unnecessary, because errors are indications of the learner's current hypothesis, which may not necessarily match the target rule, or they may indicate that no hypothesis has yet been formulated by the learner. Explicit correction may be harmful because students can be pushed beyond their competence to perform or may be forced into using a cognitive system not equipped for language acquisition. Some research has shown that students want their errors to be corrected, but this may be a reflection of a general anxiety about learning. Indirect correction may be effective when students have time to reflect or monitor, as with written assignments, but it will be effective only if the student's rule is critical or is very simple and has been learned through his problem-solving mechanism. Many teachers feel that error correction is an impetus for improvement, but the learner's innate language acquisition device will slowly guide him to the correct hypothesis. (MSE)