Children with hemiplegic cerebral palsy (CP) have impairments in bimanual coordination above and beyond their unilateral impairments. Recently we developed hand-arm bimanual intensive therapy (HABIT), using the principles of motor learning, and neuroplasticity, to address these bimanual impairments. A single-blinded randomized control study of HABIT was performed to examine its efficacy in children with hemiplegic CP with mild to moderate hand involvement. Twenty children (age range 3 y 6 mo-15 y 6 mo) were randomized to either an intervention (n=10: seven males, three females; mean age 8 y 7 mo, SD 4 y) or a delayed treatment control group (n=10: seven males, three females; mean age 6 y 10 mo, SD 2 y 4 mo). Children were engaged in play and functional activities that provided structured bimanual practice 6 hours per day for 10 days. Each child was evaluated immediately before and after the intervention, and again at 1-month post-intervention. Children in the intervention group demonstrated improved scores on the Assisting Hand Assessment, increased involved extremity use measured using accelerometry and a caregiver survey, bimanual items of the Bruininks-Oseretsky Test of Motor Proficiency, and the simultaneity of completing a draw-opening task with two hands (p<0.05 in all cases). The results suggest that for this carefully selected subgroup of children with hemiplegic CP, HABIT appears to be efficacious in improving bimanual hand use.