The mobility of domain walls in YFeO3is determined by calculating the damping of the uniform precession or k=0 spin‐wave mode. The presence of antisymmetric exchange is explicitly taken into account in obtaining the spin‐wave modes. The dominant spin‐wave damping mechanism is found to be a four‐magnon scattering process. This process leads to a calculated wall mobility that has the same order of magnitude and temperature dependence as that observed.