Abstract: Universal tool holder coolant delivery adapters have adapter bodies which are removably attachable to a tool holder by at least one fastening device, the adapter located between an attachment end of the tool holder and a distal end of the tool holder, the distal end of the tool holder having a cutting tool attached thereto, the adapter bodies having an internal coolant passageway including an intake port and an exit port, the intake port adapted for attachment to a pressurized coolant supply line and the outlet port adapted for attachment to or configured in the form of a coolant spray nozzle, the coolant spray nozzle being closely positioned and substantially aligned with the cutting interface of the cutting tool and a workpiece.