Critical Periods After Stroke Study (CPASS)

To perform an exploratory single center randomized study that will form the basis for a larger scale, more definitive randomized clinical trial to determine the optimal time after stroke for intensive motor training. The investigators will perform a prospective exploratory study of upper extremity (UE) motor training delivered at higher than usual intensity at three different time points after stroke: * early (initiated within 30 days) * subacute/outpatient (initiated within 2-3 months) * chronic (initiated within 6-9 months) The control group will not receive the therapy intervention during the 1-year study. Outcome measures will be assessed at baseline, pre-treatment, post-treatment, 6 months and one year after stroke onset. Compared to individuals randomized during the outpatient (2-3 months after stroke onset) or chronic (6-9 months after stroke onset) time points, participants randomized to early intensive motor training will show greater upper extremity motor improvement measured at one year post stroke.