Effective treatment for children with cerebral palsy requires a careful analysis of the behavior taking into consideration the complex issue of using the hands. In addition, it is important that the treatment is grounded in well-defined theories and methods. With the assistance of the International Classification of Functioning, the ICF, examples are provided of the effect of treatment on the level of Body Function. On the Activity Level, examples are given of treatment that applies recent knowledge of motor control and principles of motor learning. This paper is not intended to be a review of the literature, but rather, a set of examples from basic science, clinical practice and studies of intervention that highlight the possibilities of improving the usefulness of the hands in daily life.