An aromatic copolyester composed of 25 mol % phenyl hydroquinone, 10 mol % isophthalic acid, 40 mol % chloroterephthalic acid, and 25 mol % t-butyl hydroquinone (PICT) has been synthesized. This amorphous, glassy polymer is soluble in common organic solvents such as methylene chloride. Thin, solution-cast films may be prepared which are in a metastable, vitrified, optically isotropic state. On first heating of an isotropic film at 20 degrees C/ min in a calorimeter, one glass transition is observed at low temperature (approximately 49 degrees C) and is ascribed to the glass/rubber transition of the metastable, isotropic polymer. This thermal event is followed by a small exotherm due to the development of order during the scan, which results in a second T-g at approximately 125 degrees C. This T-g is associated with the glass/rubber transition of the ordered polymer. Nematic order can be developed by thermal annealing. The lower T-g increases toward the upper T-g as annealing time is increased. For an initially isotropic film annealed at 90 degrees C, the increase of the lower T-g with annealing time and the increase in birefringence observed by optical microscopy are governed by similar kinetics. Isotropization occurs in the temperature range of 250-300 degrees C. The nematic polymer is slightly more dense than its isotropic analog. No detectable differences between isotropic and nematic samples were observed in rotating frame proton spin lattice relaxation times.