This atlas contains the ultraviolet spectra of 70 quasars, blazars, and Seyfert 1 galaxies that were produced by combining over 100 low resolution spectra from the International Ultraviolet Explorer (IUE) data archive. The spectra have been extracted with an optimal algorithm (see Kinney et al. 1991) and co-added to produce spectra with the best possible signal-to-noise ratio. Introduction: The spectra file currently present in this directory are the digital versions of the spectra that were extracted and co-added for the Ultraviolet Atlas of Quasar and Blazar Spectra, 1991 (reference above) The files contain the optimally extracted data which are described in "Weighted Slit Extraction of Low Dispersion IUE spectra. The optimal extraction is described in A. L. Kinney, R. C. Bohlin, and J. D. Neill 1991PASP..103..694K Each co-added spectrum consists of the wavelength, quality flag, gross flux, background flux, gross flux divided by time, absolutely calibrated net flux, exposure time, and sigma. Details from the headers which formerly prefixed each spectrum are in headers.dat. A third file (objects.dat) is also available, which contains information from Table 1 in the published paper: IAU and alternate designations, redshift (z), V magnitude, object type, E(B-V), galactic longitude and latitude, and number of spectra. The file formats are mostly self explanatory. THE S-AP NOMENCLATURE INDICATES THE SPECTRA THAT ARE NORMALIZED IN FLUX TO THE L-AP SET (USUALLY ONE SPECTRUM, see paper for a more detailed explanation) AND DOES *NOT* MEAN THAT THE SPECTRA WERE OBTAINED IN THE SMALL ENTRANCE APERTURE. The camera numbers of co-added spectra are listed. Each co-added spectrum has 8 columns of ASCII numbers with the titles.