Children with cerebral palsy (CP) display postural problems, largely interfering with daily life activities. Clarification of neural mechanisms controlling posture in these children could serve as a base for more successful intervention. Studies on postural adjustments following horizontal forward and backward displacements of a movable platform in ten school-age children with spastic diplegia and non-disabled controls revealed that sitting CP children, like standing CP children, show direction specific postural adjustments, indicating that the basic pattern of muscle coordination in these conditions is conserved. Dysfunctions are especially present in the modulation of the response pattern of ventral muscles during forward translations. They consist of: (1) a stereotyped and non-variable activation of all ventral muscles; (2) an abnormal top-down muscle recruitment; and (3) an excessive degree of antagonistic co-activation. The altered patterns of muscle coordination could be the result of two interacting mechanisms, the primary deficit due to the early brain damage and a compensation due to the postural instability. Especially the latter dysfunction furnishes opportunities for therapeutic help.