The optimal management of the adult acquired flatfoot requires careful assessment of the deformity. Although it is essential to recognize the location and degree of malalignment, it is of equal importance to appreciate whether the deformity is flexible or rigid. For patients undergoing surgery for a flexible flatfoot, various soft tissue procedures and bony osteotomies may be used to restore alignment while preserving joint motion. However, for patients undergoing surgery for a rigid deformity, such procedures are indicated less often, and arthrodesis is usually necessary.