The interactions between poly(ethylene terephthalate) (PET) and six high temperature solvents are discussed in terms of gelation and melting temperature depression. The six solvents are 1’-acetonaphthone (AN), phenyl ether (PE), biphenyl (BP), 1-methyl naphthalene (MN), nitrobenzene (NB), and a eutectic mixture of phenyl ether and biphenyl (EU). Although the six solvents have very similar solubility parameter values, the dissolution, gelation, and gel melting temperatures of the PET-solvent systems are vastly different. The characteristic transition temperatures (dissolution, gelation, and gel melting temperatures) of the six solvents decrease in the following order : PE > EU > BP > MN > AN > NB, which is the reverse order of the solvent power. While the transition temperatures of the gel vary with the solvent system, the melting temperature of the dry gel formed from quiescent solution is independent of solvent system. That is, PET-solvent interactions are only discernible in solvated state (wet gel). All the experimental results suggest crystallization is the primary cause of gelation of high temperature PET solutions, with crystals acting as junction points in the network. Based on the dissolution and gel melting temperatures, interaction parameters for the six PET-solvent systems have been calculated.