Do expansive body postures increase self-esteem in children? Power posing is a popular but also controversial topic. Still, there has been no research on the possible effects in children. To investigate the influence of power posing in children, 108 German fourth graders were randomly assigned to a high versus a low power posing group. Self-esteem was self-reported; feelings were assessed indirectly. There was an effect of power posing on self-reported global and school self-esteem. Furthermore, children who had performed high power poses in comparison with those who had performed low power poses mentioned more positive feelings, higher power feelings, and a more positive student–teacher relationship. Results are interpreted with regard to the context and the cultural dependency of the power posing effect. Implications for school practice are addressed.