The vibrational relaxation of noble gas–halogen van der Waals clustershas been fertile territory for the development of experimental and theoreticaltools for state-to-state dynamics studies. Proceeding through the variouscombinations of noble gas atoms and halogen molecules, one goes from“simple” direct vibrational predissociation, through sequentialrelaxation pathways, to the statistical intramolecular vibrational relaxationlimit. In some cases the vibrational processes dominate, in otherselectronically nonadiabatic processes, including chemical reactions, interfere.Thus the noble gas–halogen species provide test cases for most of thedynamical processes available to more “normal” molecules. Thisreview discusses the current state-of-the-art for such studies and points toimportant problems that remain to be solved.