The increasingly diverse language backgrounds of their students are creating new challenges for English-medium universities. One response in Australian and New Zealand institutions has been to introduce post-entry language assessment (PELA) to identify incoming students who need to enhance their academic language ability. One successful example of this type of programme is the Diagnostic English Language Needs Assessment (DELNA) at the University of Auckland, which has been implemented across the university since 2002. This paper discusses the reasons for introducing the assessment and outlines its current operation. As part of the validation process feedback is obtained from academic staff, and from students who have completed the assessment and been advised about their opportunities for enriching their academic literacy. The focus of this paper is on the ways the feedback has led to changes both in the composition and administration of the assessment and the delivery of effective English language programmes.