We report on optical spectroscopy of 459 Fermi blazars—164 Flat Spectrum Radio Quasars (FSRQs) and 295 BL Lacertae Objects (BL Lacs) drawn from the First and Second Fermi LAT AGN Catalogs. In this largest ever optical spectroscopic study of blazars, we show that Fermi FSRQs have smaller virial estimates of black hole mass than the optical quasar sample. This appears to be largely due to a preferred (axial) view of the gamma-ray FSRQ and nonisotropic (H/R ~0.4) distribution of broad-line velocities. Even after correction for this bias, the Fermi FSRQs show higher mean Eddington ratios than the optical quasar population.

We further report on the non-thermal dominance of the optical spectrum in both FSRQs and BL Lacs, the degree depending on the gamma-ray hardness. We detect (or constrain the amplitude of) host galaxies for the BL Lacs. We find systematically fainter galaxy hosts for BL Lacs than previous studies, suggesting that this gamma-ray selected sample probes a less luminous population than optically selected samples. These data give redshifts for many of the BL Lacs and significant redshift constraints for the remainder of the population. These extend to substantially higher z than the previously measured subset of this sample. Finally, we discuss the black hole masses of Fermi blazars, and comment on the use of this sample for studies of BL Lac evolution and the extragalactic background light.