The long-term objective is to conduct comparative efficacy research to identify the possible mechanisms and the relative effectiveness of existing rehabilitation approaches of fully defined-, evidence-based, and theory-grounded approaches. This proposed project aims to (1) compare the effects of dose-matched unilateral vs bilateral vs unilateral combined with bilateral upper limb rehabilitation based on task-related practice; (2) compare the effects of unilateral vs bilateral training based on robot-assisted devices; and (3) study the predictors of treatment outcomes and clinimetric properties of the biomechanical measures. The outcome measures will span the spectrum of health-related functioning, including motor and neural control, movement performance, daily functions, and quality of life. Motor and neural control mechanisms involving movement strategies, muscle and force output, and brain reorganization will be evaluated using kinematic, electromyographic (EMG), and kinetic analyses, and also functional magnetic resonance imaging (fMRI) examinations. Clinical outcomes will include movement performance, daily functions, and quality of life, measured by MYOTON-3, Modified Ashworth Scale, the Fugl-Meyer Assessment, Wolf Motor Function Test, Functional Independence Measure, ABILHAND questionnaire, accelerometers, and Stroke Impact Scale. This 5-year project will recruit an estimated 200 patients with stroke. For Part 1, 120 patients with mild-to-moderate motor impairment will be randomized to the dose-matched unilateral, bilateral, or combined group. For Part 1, 80 stroke patients with moderate motor impairment will be randomized to the dose-matched unilateral or bilateral robot-assisted therapy group. Treatment regimens will be designed to ensure that patients in the 3 groups in Part 1 and 2 groups in Part 2 receive an equivalent intensity of treatment (5 days/week for 1.5 hours/day for 4 consecutive weeks). The intervention will be provided at 4 hospitals. Two certified occupational therapists will be trained in the administration of the 5 types of rehabilitation protocols by the PI and a co-PI and will complete a written competency test before subject treatment.