Critical Periods After Stroke Study (CPASS)

Inclusion Criteria: * Ischemic or hemorrhagic stroke (with confirmatory neuroimaging) within 28 days of admission to inpatient rehabilitation (allows those randomized to the early arm to begin study-related treatment within 30 days) * Age \>21 years * Able to participate in first study-related treatment session within 30 days of stroke onset * Able to participate in all study-related activities, including one year follow up and blood draws * Persistent hemiparesis leading to impaired upper extremity function. Hemiparesis as indicated by NIHSS Motor Arm score ≥ 1 * Recovering moderate motor impairment at the shoulder and elbow or hand such as: * Proximal UE voluntary activity indicated by a score of ≥ 3 on the upper arm item of the Motor Assessment Scale - wrist and finger movement is not required or * Manual Muscle Test (MMT) score of ≥ 2 on shoulder flexion or abduction and MMT score of ≥ 2 for any of the following: elbow flexion, elbow extension, wrist flexion, wrist extension, finger flexion or finger extension. or * Active range of motion (AROM) to at least 50% of range in gravity eliminated position for shoulder flexion or abduction, and for any of the following motions: elbow flexion, elbow extension, wrist flexion, wrist extension, finger flexion or finger extension. * Score of ≤ 8 on the Short Blessed Memory Orientation and Concentration Scale * Follows 2 step commands * No upper extremity injury or conditions that limited use prior to the stroke * Pr…