The Heat Resistant Alloys Subcommittee of the High Alloys Committee of the Welding Research Council through the Results of its Weldability Testing Survey found that the Varestraint Test@ or one of its various modifications@ is the most utilized weldability test for evaluation of hot cracking sensitivity. The subcommittee also noted that the many Varestraint Test techniques have not been addressed in a single document which would be useful for potential test users. Therefore@ it was decided to present the experience of several researchers in a monograph devoted to Varestraint testing. The basic underlying tenet is: to encourage the use of weldability testing; to give prospective users the benefits of the experience of those who have employed the test; to alert potential users to the advantages and pitfalls inherent in the currently utilized techniques and to outline the important test variables and the evaluation criteria. Thus@ this monograph is not intended to be a standardization document but a utilization guide.