We report on the rapid thermal processing (RTP) of YBa2Cu3O7 (Y-123) fibers. Unsintered fibers are densified by RTP. We show that fibers which were originally semiconducting and tetragonal before RTP form normal twinned orthorhombic material after processing for 2–4 seconds above 1000°C with a 3 min. cool down in oxygen. They subsequently show Tc to 90K and magnetization indicative of substantially shielding. We present the effects of varying the RTP parameters on the morphology, phase, and superconducting properties of a number of tetragonal and orthorhombic Y-123 fibers.