SAFIRE is a versatile imaging Fabry-Perot spectrograph covering 145 to 655 microns, with spectral resolving powers ranging over 5 - 10,000. Selected as a `PI' instrument for the airborne Stratospheric Observatory for Infrared Astronomy (SOFIA). SAFIRE will apply 2D pop-up bolometer arrays to provide background-limited imaging spectrometry. Superconducting transition edge bolometers and SQUID multiplexers are being developed for these detectors. SAFIRE is expected to be a `First Light' instrument, usable during the initial SOFIA operations. Although a PI instrument rather than a `Facility Class' science instrument, it will be highly integrated with the standard SOFIA planning, observation, and data analysis tools.