Irradiated accretion disks around massive black holes are expected to produce part of the line spectrum of AGN, but most of the disk emission must be thermal, observed at UV wavelengths. The two emission components, lines and continuum, are fitted by a unique accretion-disk model that gives the mass of the black hole and the inclination of the disk. The distribution of the disk inclination in a complete sample of Seyfert 1 galaxies suggests that their nuclei are orientation-selected, affected by strong absorption at low disk latitudes. The black-hole masses in the same sample confirm the long-standing non-linearity between M and L for AGN and the non-causal relationship between nearby Seyfert 1 galaxies and distant quasars (i.e., pure luminosity evolution is ruled out).

Irradiated accretion disks are also combined with the relativistic jet model in order to constrain the orientation and the Lorentz factor of 14 superluminal radio sources. At least for a few objects, the line and the radio data are inconsistent with both models, unless a new parameter (jet bending, a second emission-line component, etc.), is also involved. Despite this inconsistency and the ambiguous evidence for combined disk and jet fits in the remaining superluminal sources, a successful merger of these two models might address questions about the nature of AGN and also constrain the Hubble constant.