This paper will deal, firstly, with the South African context, that cries out for attention to responsible language assessment. The renewed interest in language testing in South Africa is well illustrated in assessments of language ability for educational purposes generally, and more specifically in the assessment of academic literacy. Secondly, the paper presents a meaningful reminder that the assessment of academic literacy in South Africa brings: the benefits of paying diligent attention to the articulation of the construct. This is evident both in the descriptions of the major themes in language assessment in South Africa, and in some commentaries in the international literature about developments here. Finally, the paper describes the way that we are starting to deal with the validation of language tests from the vantage point of a theory of applied linguistics, rather than from the sometimes inconclusive debates on validity. In all three respects, there may be productive insights for those working in other contexts. The most important insight, perhaps, comes from relating the validation of these assessments to a theory of applied linguistics, indicating a way in which test designers may operationalize and satisfy a number of further conditions for their responsible design of language tests.