Abstract: Tool holder having a row of spaced tool supporting sockets each adapted to receive and support in an upright position therein the shank portion of one of a series of drill bits of increasing diametrical size from one end to the other end of the row. The tool holder includes a second row of tool supporting sockets spaced from the first row and adapted to receive and support in an upright position therein the shank portion of one of a series of thread cutting taps of increasing diametrical size from one end to the other end of said second row. Indicia are provided which extend from each tap socket toward a predetermined correlative pair of spaced drill sockets. Each such pair of drill sockets is adapted to retain therein the proper tap drill and clearance drill for each corresponding tap.