We have carried out an extensive program of observations of the ionized gas in 74 luminous elliptical and lenticular galaxies, selected to include a variety of properties in radio and X-ray emission, and in kinematical behavior. For each galaxy we have obtained broad-band R and V images and narrow-band images, centered at the Hα and [NII] emission lines, to derive the luminosity and distribution of the ionized gas. We found that a large fraction (≃ 70%) of E and S0 galaxies in our sample contain ionized gas. The gas morphology and size varies from small disks (mean diameter 1 – 4 kpc) to large filamentary structures (extending up to 10 kpc from the galaxy center). Comparison with previous measurements shows reasonable agreement for a few galaxies, but considerable scatter for a large fraction, possibly due to differences in the limiting flux thresholds.