Because schools worldwide use low-stakes tests to make important decisions, value-added indices computed from test scores must accurately reflect student learning, which requires equal test-taking effort across testing occasions. Evaluating change in effort assumes effort is measured equivalently across occasions. We evaluated the longitudinal measurement invariance of a globally used self-report measure of test-taking effort. Given measurement invariance, we assessed average change and variability in change in effort when examinees completed the same low-stakes tests twice during college. Average effort declined slightly, but there was large variability in change in effort. Conscientiousness, agreeableness, openness, and performance-approach orientation were uncorrelated with change in effort. Initial effort, change in mastery-approach orientation, change in work-avoidance orientation, and change in perceived test importance were correlated with change in effort. Because change in test importance had the strongest relationship with change in effort, globally applicable interventions to increase effort through increasing test importance are discussed.