Glass transition temperatures (Tg) play an important role in the fields of coatings and adhesives. Powder coatings with a low Tg would sinter in shipping while adhesives or sealants with too high a Tg may be too brittle or would not seal properly. Equations are presented which express <i>(a) the Tg of a copolymer in terms of the Tg of homopolymers prepared from its constitutent monomers, <i>(b) in terms of weighed contributions derived from the various copolymer sequences possible. For some copolymers treatment <i>(a) is sufficient, but for others <i>(b) must be employed, indicating that the copolymer microstructure is affecting macroproperties. Using approach <i>(b) Tg are correctly predicted for copolymers of alpha-methylstyrene/acrylonitrile. -- AATA