A system is provided for controlling slip of a ground-engaging traction device of a work machine. The system includes an actual slip calculator operable to transmit an actual slip signal corresponding to an actual slip experienced by the work machine. The system also includes a ground condition selector operable to transmit a ground condition signal corresponding to a selected ground condition. A desired slip calculator is operable to transmit a desired slip signal based on the ground condition signal. A slip controller is coupled with the actual slip calculator and the desired slip calculator. The slip controller is operable to transmit a slip control signal based on the actual slip signal and the desired slip signal. The slip control signal controls the actual slip experienced by the work machine to achieve the desired slip.