  Recent years have seen tremendous progress in the quest to detect
supermassive black holes in the centers of nearby galaxies, and gas-dynamical
measurements of the central masses of active galaxies have been valuable
contributions to the local black hole census. This review summarizes
measurement techniques and results from observations of spatially resolved gas
disks in active galaxies, and reverberation mapping of the broad-line regions
of Seyfert galaxies and quasars. Future prospects for the study of black hole
masses in active galaxies, both locally and at high redshift, are discussed.
