The aim of this study is to explore the possibility of creating positive washback by focusing on factors in the background of the test development process and anticipating the conditions most likely to lead to positive wash-back. The article reports on a multiphase empirical study investigating the washback effects of a needs-based test of spoken language proficiency on the content, teaching, classroom activities and learning outcomes of the ITA (international teaching assistants) training program linked to it. As such, the conceptual framework underlying the study differs from previous models in that it includes the processes before test development and test design as two main components of washback investigation. The analysis of the data--collected from different stakeholders through interviews, observations and test administration at different intervals before, during and after the training program--suggests a positive relationship between the test and the immediate teaching and learning outcomes. There is, however, no evidence linking the test to the policy or educational changes at an institutional level.