The experimental tools are now at hand to allow characterization of oligomerizing enzymes. There is reason to believe that a great many enzymes belong to this class even though their characterization may be incomplete. The data presented here and elsewhere establish the biodegradative L-threonine dehydrase as a simple three-variable oligomerizing system which can serve as a useful and reasonably well documented model. The criteria presented above can be applied by investigators if the techniques are available to handle these usually inherently labile systems. It is hoped that the information given will aid the investigation of kinetics and thermodynamics of these very dynamic systems.