In a 1983 paper in thisJournal (A19, 693), Ham questioned the existence of ternary azeotropes. A recent paper by Quella[Makromol. Chem., 190, 1445 (1989)J has criticized the earlier thesis, in part on the basis that Ham's “indications have certainly not encouraged the search for ternary azeotropes,” and on the basis of “further experimental results from other authors”. This paper responds to Quella, further develops evidence against ternary azeotropes, and, in addition, discusses pertinent terpolymer interactions in terms of terpolymerization probabilities and in terms of general monomer reactivities.