This paper raises questions about the significance of errors made by language learners. The discussion is divided into four parts: (1) definition of error analysis, (2) the present status of error analysis research, including an overview of the theories of Lado, Skinner, Chomsky, Corder, Nemser, and Selinker; (3) the subdivisions of error analysis research, and (4) the pedagogical consequences of error analysis. In the last part of the paper, the need for teachers to be more conscious of their students' errors and to see these errors as evidence of learning is emphasized. (PMP)