Abstract: An adapter assembly incorporating the lower chuck end of a rotary impact tool unit, the support means thereof, and the tool bit extending from the lower end thereof. The impact tool unit is of the general type in which the impact motor is not connected directly to the outer support housing but is mounted for upward axial movement in the housing, as a result of recoil forces, to substantially reduce shock and vibration transmitted to the operator who holds the unit by means of a handle carried by the housing. The adapter assembly cooperates with the tool bit to hold it down against the work but permits the tool bit to rotate or oscillate about its axis or to remain in a stationary position angularly relative to the axis.