We are designing and building state-of-the-art robot hands that aim to replicate the functionality of the human hand. These include the Anatomically Correct Testbed (ACT) hand, which is the most realistic robot hand available, that closely mimics the joint kinematics and tendon networks of the human hand. Emo Todorov's group recently joined this effort, building the Modular Robot (ModBot) hand, whose fingers have characteristics similar to haptic robots in terms of speed and compliance while being designed for manipulation. We are now developing the next generation of robot hands, using frictionless pneumatic cylinders, simplified tendon arrangements, and 3D-printed joints based on scans of human hands.