High-stakes language tests are used by immigration authorities, professional registration bodies and employers to make decisions about the employability of non-native speakers of English in English speaking countries. Additionally, native speakers of English are required to take high-stakes language tests to gain immigration points or for professional registration purposes. However, there is a paucity of research on the perceptions of native speaker test takers, non-native speaker test takers and employers regarding the test content and constructs being measured in English language tests compared with the language used in the contemporary workplace. This thesis, therefore, addresses the research question: To what extent are language assessment test scores used in valid and ethical ways for the purpose of immigration, employment and professional registration in a New Zealand context? There has also been little research into language test validity using an argument-based approach. This research study attempts to fill this void by applying an argument-based validation approach to a high-stakes language test, the International English Language Testing System, which is currently widely used for employment, professional registration and immigration purposes in New Zealand. Four sub questions were developed as the research progressed to encompass domain, extrapolation, decision, and consequence inferences. The data which provided evidence for these inferences were collected from semi-structured interviews with stakeholders who had taken or used the test for employment purposes. Their perceptions provided support or rebuttal for the inferences in the validation argument. The ensuing results helped build an argument which clarifies the extent to which language test results are being used in valid and ethical ways for employment purposes.

The perceptions of the non-native speaker test takers, and particularly the native speaker test takers and employers highlight the social, economic and political implications of using language tests to infer the communicative language competence of migrants in three employment sectors: education, business/IT and manufacturing/retail. Recommendations are made for the future use of language tests which assess higher language cognition and communication skills as opposed to basic communicative language competence. The insights gained from this research demonstrate that native speakers of English support the testing of oral language skills, but that the ways in which written language skills are used in the contemporary workplace have changed. As a result, there is a strong need for language test developers and test users to engage in collaborative discussions in order to ascertain which types of current and future written language skills should be tested for migration and employment in English-speaking countries.