Employee responses to cross-border mergers and acquisitions are an important factor determining the success of post-merger integration. However, little research exists investigating employee responses in this phase. Our study examines employee responses to an acquisition by investigating the role of social support from different hierarchical levels to predict employees’ work attitudes after acquisition. Survey results of 186 Korean employees of an acquired firm show that the influence of social support varies depending on its source level in the hierarchy. While top management and supervisor support had positive effects on employees’ work attitudes, co-worker support was insignificant.