A powered rope ascender that supports a person or a load while ascending a vertical rope. The rope ascender has a motor driven capstan drum that engages the rope. A pinch roller grips the rope against the capstan drum. A load limiting assembly releases the grip by the pinch roller when the load supported by the ascender exceeds a predetermined amount. A centrifugal clutch reduces starting torque required by the motor and the outer drum of the centrifugal clutch interacts with a brake to hold position on the rope. For heavy loads a motion activated brake is used. Hand controls provide a freewheeling, a braking and an ascending mode of operation. A harmonic drive or planetary reduction gears provide speed reduction from the motor to the capstan drum. The powered rope ascender can be threaded on the rope without access to a rope end.