Although ankle–foot orthoses (AFOs) are frequently prescribed to correct skeletal malalignment in children with spastic diplegia, their effect on standing balance abilities has not been documented. This study investigated balance differences related to the presence of pathology and orthotic conditions during conditions of unexpected stance perturbation by comparing four children aged between 3½ and 15 years with spastic cerebral palsy and four control children matched for years of independent walking experience. Electromyographic and kinematic data were collected and compared between groups and in three orthotic conditions (no AFOs, solid AFOs, dynamic AFOs). Results revealed that balance responses of children with spasticity were characterized by: increased coactivation of muscles as opposed to distal to proximal recruitment, decreased presence of upright posture in stance, increased use of ‘on-toes’ strategies, and different sway characteristics compared with the typically developing children. In both groups of children, the use of solid AFOs during perturbed stance resulted in: decreased activation of gastrocnemius muscles, disorganized muscle-response patterns, decreased use of ankle strategies, and increased joint angular velocities at the knee compared with conditions without AFOs or with dynamic AFOs. These preliminary results support the use of dynamic AFOs to correct skeletal malalignment in children with spastic diplegia.