The thread engagement verifier system provides for verifying the quality of a threaded connection 12 between upper and lower for tubular member 16, 18. One or more thermal radiation sensors 14 are used in combination with a data acquisition and processing computer 20 and an output device, such as a video display 12. The thermal radiation is generated by sliding friction between the tubular members, and the sensors 14 sense radiation at a plurality of external locations and output heat intensity signals to the computer 20. Torque may also be sensed via a sensor 32 and input to the computer 20.