There is described hybrid powertrain operation and control. Preferred power flows from an engine to an electro-mechanical transmission and from an energy storage system to an electric machine are determined based upon an operator torque request. Operation of the engine, the electric machine, and the electro-mechanical transmission are controlled to substantially meet the operator torque request. Actual power flow from the energy storage device is monitored. The power flow from the engine is adjusted based upon a difference between the actual and preferred power flows from the energy storage device.