This article shares and extends research-based developments at the University of Otago, New Zealand, that seek to explore how students' worldviews change as they experience higher education with us. We emphasise that sustainability attributes may be described in terms of knowledge, skills and competencies but that these are underpinned by affective attributes such as values, attitudes and dispositions; so that "education for sustainable development" is substantially a quest for affective change. We describe approaches to categorise affective outcomes and conclude that "education for sustainable development" objectives comprise higher order affective outcomes (leading to behavioural change) that are challenging for higher education to address. Our own work emphasises the need for student anonymity as these higher order outcomes are assessed, evaluated, monitored, researched or otherwise measured using research instruments that focus on worldview. A longitudinal mixed-effects repeat-measures statistical model is described that enables higher education institutions to answer the question of whether or not "education for sustainable development" objectives are being achieved. Discussion links affect to critical reasoning and addresses the possibility of documenting and assessing the development of lower and mid-order affective outcomes. We conclude that "education for sustainable development" objectives need to be clearly articulated if higher education is to be able to assess, or evaluate, their achievement.