The glass transition behavior of five different epoxies, commercially available as primers and saturants for FRP strengthening systems, have been investigated using dynamic mechanical analysis. Glass transition temperatures, Tg, were assigned using three methods: storage modulus onset, loss modulus peak, and tan δ peak. Based on the Tg values, a comparison of the five epoxies as well as the three different methods of T g assignment were made. It was observed that post-curing during the DMA test procedure can have a dramatic effect on the glass transition behavior, with Tg values increasing up to 22° C on two short exposures to the maximum test temperature. For a given product, the difference in T g values as a function of test method ranged from 12°C to 42°C on the first thermal cycle. Two Tg values were observed for one of the products, indicating the presence of secondary polymer as a blend or copolymer. Epoxy polymers used as saturants showed a higher transition temperature than those used as primers and adhesives.