Abstract: An outrigger assembly having a mounting portion mountable directly to a dump trailer suspension system. In one embodiment, the mounting portion is mounted directly to leaf springs of a suspension system. Two stabilizing arms are pivotably attached to the mounting portion. A driving mechanism is connected to the stabilizing arm and configured to move the stabilizing arms between an inward, stowed position, and an extended, stabilized position. The stabilizing arms being shaped and sized to engage the ground outboard of the dump trailer wheel base to increase the effective width of the dump trailer's support base, thereby stabilizing the dump trailer from tipping.