Resumen
The article deals with the complexity of a washback phenomenon in language testing. It focuses on its positive effects within an institution as well as on the situations of negative washback. Washback is presented as a stimulus for a change and as a bridge for efficient communication between teachers and testers. Certain changes as a result of positive washback point at the opportunities which a testing institution has when it organizes, designs and administers criterion-referenced tests.The complexity of washback is confirmed when the teachers' perspective is discussed. Teacher-tester relationship and the lack of teacher insight into testing may contribute to negative washback. Within this frame, concrete situations are described and lessons learned are summarized. In the conclusion, the teachers and testers are reminded of professional and ethical standards and of their responsibility towards their clients, students and test takers.