A thin disk illuminated by a central source will produce single-peaked broad emission lines if there is a wind emerging from the disk. The velocity gradient in the wind produces an anisotropic optical depth. For optically thick lines, the emission is strongest along directions perpendicular to the Keplerian velocity of the disk. The resulting line profiles are single peaked even though the emitting gas moves on essentially circular orbits. We argue that the broad emission lines seen in quasars, Seyferts, and luminous cataclysmic variables arise in disk winds.