Within self-regulated learning, learners exercise agency by setting targets, formatively monitoring progress, and evaluating results in ways which inform their own goal attainment. However, in real-world classroom situations, assessment processes can elicit behaviours that are more ego-protective than growth-oriented. Resistance to teacher expectations in assessment can arise from the individual's need to protect his or her own identity or ego within the psychosocial context of the classroom. In addition, resistance can arise from strategic choices learners make to cope with competing demands on their time and resources. Thus, students may exercise their agency by not following assessment expectations or protocols (e.g. lying, cheating, or failing to give their best effort). These choices seem to undermine assessment validity. This paper shares student voice data from the Measuring Teachers' Assessment Practices (MTAP) project (n = 46 students in seven focus groups) in New Zealand and the Supporting Student-assessment Success (SSAS) Project (n = 108 first-year university students) in Australia. Both highlight the different ways students resist, subvert, or act in contention with assessment. These data show that students in both sectors do not always act in the growth-oriented ways that educators envision. Students reported exercising potentially maladaptive assessment agency via "Assessment dishonesty," "Purposeful underperformance," and "Doing it alone." These categories were underpinned by three differing rationales: "Protection," "Strategic prioritisation," and "Mini-max." Educators must be mindful of these potential student actions and motives, working to establish psychological safety within the learning environment, and making sure links between learning and assessment are clear.