The present electromyographic study is a first step toward shedding light on the involvement of affective processes in congruent and incongruent facial reactions to facial expressions. Further, empathy was investigated as a potential mediator underlying the modulation of facial reactions to emotional faces in a competitive, a cooperative, and a neutral setting. Results revealed less congruent reactions to happy expressions and even incongruent reactions to sad and angry expressions in the competition condition, whereas virtually no differences between the neutral and the cooperation condition occurred. Effects on congruent reactions were found to be mediated by cognitive empathy, indicating that the state of empathy plays an important role in the situational modulation of congruent reactions. Further, incongruent reactions to sad and angry faces in a competition setting were mediated by the emotional reaction of joy, supporting the assumption that incongruent facial reactions are mainly based on affective processes. Additionally, strategic processes (specifically, the goal to create and maintain a smooth, harmonious interaction) were found to influence facial reactions while being in a cooperative mindset. Now, further studies are needed to test for the generalizability of these effects. (PsycINFO Database Record (c) 2011 APA, all rights reserved)