A deficit of the anterior interosseous nerve (AIN) limits one’s ability to flex the thumb IP joint and index finger DIP joint, severely impairing pinch, grasp, and fine-motor dexterity. The radial nerve branch to the extensor carpi radialis brevis (ECRB) may be transferred to the AIN to reinnervate the flexor pollicis longus and index finger flexor digitorum profundus. The ECRB-to-AIN nerve transfer is a reliable procedure that promotes the restoration of functional pinch and grasp. Postoperative therapy includes three phases based on the donor activation focused rehabilitation approach. Therapy progresses based on manual muscle strength testing of the recipient FPL and index finger FDP muscles. Trace muscle contraction may initially become evident at the FPL 3–4 months following surgery, and it may take 12–24 months to achieve functional movement.