The strategy in rehabilitating pediatric hemiplegia is to overcome "developmental disuse". Disruption of the excitability in the non-stroke hemisphere, with resultant increased excitability (disinhibition) in the stroke hemisphere, can be achieved with low-frequency repetitive transcranial magnetic stimulation (rTMS), a noninvasive method of stimulating targeted areas of the brain. Furthermore, the disruptive effects of low-frequency rTMS can be increased and prolonged by preceding it with 6-Hz priming stimulation. We have recently demonstrated the safety of this priming/low-frequency rTMS in adults with stroke and we are currently engaged in an NIH-funded study exploring the effectiveness, mechanism and safety of serial treatments of rTMS combined with motor learning training. Very little research, however, has been attempted on interventions to promote brain reorganization and recovery in hemiplegia in children. Thus, this study will determine the effectiveness, mechanism, and safety of 5 treatments of 6-Hz primed low-frequency rTMS applied to the non-stroke hemisphere and combined with constraint induced therapy (CIT) to promote recovery of the paretic hand. Fifteen children with pediatric hemiplegia, age 8 -16 years, at each of two pediatric medical facilities (total N = 30), will be randomly assigned to one of two treatment groups that will receive treatment for 2 weeks. The rTMSreal/CIT group will receive alternating days of the real rTMS and CIT for 5 treatments of each. The rTMSsham/CIT group will receive alternating days of sham rTMS with real CIT for 5 treatments of each. Subjects will be tested at pretest and posttest. The hypotheses are: 1) the rTMS treatment will show no serious side effects, 2) both groups will show improvement in hand function but the rTMSsham/CIT group will show significantly greater improvement, 3) the rTMSreal/CIT group will also show significantly greater improvements in brain reorganization measured by paired-pulse TMS testing, cortical silent period testing, and fMRI. The proposed research is important because very little research on rehabilitation-induced brain reorganization has been done in pediatric hemiplegia. It is innovative because it applies a technique never used before, i.e. 6-Hz primed low-frequency rTMS combined with CIT. The potential impact of this research is a radical change to pediatric rehabilitation that accomplishes a higher functional recovery.