The structure, morphology, and properties of the methyl pendant PBZT fiber have been studied with variations in thermomechanical treatment. For comparison, selected studies on PBZT fibers have also been carried out. Crosslinking in the methyl pendant PBZT fiber occurs in the 450-550 degrees C range under free annealing, leading to a nonfibrillar structure. Recoil compressive strength, loop strength, torsional modulus, and the transverse compressive strength of the tension heat-treated MePBZT fiber are 50 to 100% higher compared to the comparably heat-treated PBZT fiber. Compressive strength and other mechanical properties could not be measured on highly crosslinked free annealed samples, as such samples showed significant transverse cracks. Reasons for the development of transverse cracks have been discussed.