Constraint induced movement therapy (CIMT) for hemiplegia involves constraining use of the unaffected limb while providing intensive shaping and practice of movements in the hemiplegic limb. The technique had been shown to be highly effective in improving upper limb function in adults following stroke, but there is only a limited literature on the use of this intervention in children. This paper provides a brief overview of the theory and background of this procedure, and reviews the literature on use of the technique in children. It then provides detailed case reports for two hemiplegic children, ages 19 and 38 months, each of whom underwent a trial of CIMT. Both children made significant gains in upper arm function that were reflected in a variety of domains, including aspects of everyday functional limb use. Gains persisted to variable degrees and some unexpected new gains were noted following cessation of CIMT. Practical challenges for the children, parents, and therapists in implementing this intensive but promising intervention are also discussed.