This field study of a merger examines the antecedent factors and processes that explain two different forms of employee support for change—compliance and championing. Our overarching goal is to understand why some employees comply and others champion change efforts. We examine the combined effects of context and person factors on both positive and negative employee reactions to change, and then investigate the differential effects of these reactions on employee support for change. Results support our hypotheses and show that change management support (context factor) negatively predicts threat appraisals and positively predicts challenge appraisals. Both compliance and championing are positively predicted by challenge appraisals, and threat appraisals are negatively related to championing. Analyses also reveal that the positive relationship between change management support and challenge appraisal is stronger when dispositional resistance to change (person factor) is high. Moderated‐mediation analyses suggest employees’ compliance and championing for change are differentially affected by management actions, their own dispositional resistance, and that these effects are mediated through positive and negative appraisals.