 Robot-assisted therapy is on the cutting edge of stroke rehabilitation and is a therapy method that promises to improve the lives of persons with disabilities due to stroke. Preliminary studies using these tools provide mixed evidence for their effectiveness and reveal limitations. For example, inconsistent carryover of motor gains to real life activities of daily living ADLs is seen. Therefore, it is still not clear what treatment strategies maximize functional outcomes on ADLs. There is a need to study the stroke recovery process and to understand how to optimize robot-assisted therapies in order to enhance patient rehabilitation and improve functional outcomes. Imaging techniques such as functional Magnetic Resonance Imaging fMRI and Diffusion Tensor Imaging DTI can assist us in understanding the stroke recovery process, in determining who may benefit from robot-assisted training, and in defining how training induced functional cortical changes occur after robot training. We propose to conduct an interventional study plus control to assess the effectiveness of four weeks of robot-assisted practice of tasks with skilled functional tasks that involve reaching and grasping activities similar to real activities. We will examine the process of recovery for low-to-moderate functioning stroke survivors with chronic disability. We will assess the ability of active-assisted reaching and grasping training to effect immediate gains and long-term functional improvements. Further, using fMRI and DTI, we plan to associate changes seen in motor impairment levels and functional task performance levels with white matter injuries and connectivity and changes in oxygen utilization in the motor cortex as well as other areas of the brain. Our short-term aims are to, i assess short-term functional gains after practice of skilled reaching and grasping tasks; ii assess maintenance of these improvements; iii quantify the neuronal changes associated with short-term gains, and iv identify trends across high and low responders in terms of patterns of change in cortical activity and type of white matter connectivity. In the long-term, we hope to improve understanding of the process of ADL functional recovery after stroke and optimize robot-training strategies leading to cerebral plasticity. We also hope to determine how lesion characteristics affect changes seen in function, white matter connectivity, and cortical activity. By, accomplishing these aims, we hope to improve upper extremity function after stroke and reduce disability. 