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We review critically the evidence concerning the fraction of Active GalacticNuclei (AGN) which appear as Type 2 AGN, carefully distinguishing strict Type 2AGN from both more lightly reddened .Type 1 AGN, and from low excitation narrowline AGN, which may represent a different mode of activity. Low excitation AGNoccur predominantly at low luminosities; after removing these, true Type 2 AGNrepresent 58% of all AGN, and lightly reddened Type 1 AGN a further ~15%.Radio, IR, and volume-limited samples all agree in showing no change of Type 2fraction with luminosity. X-ray samples do show a change with luminosity; wediscuss possible reasons for this discrepancy. We test a very simple picturewhich produces this Type 2 fraction with minimal assumptions. In this picture,infall from large scales occurs in random directions, but must eventually alignwith the inner accretion flow, producing a severely warped disk on parsecscales. If the re-alignment is dominated by tilt, with minimal twist, a widerange of covering factors is predicted in individual objects, but with anexpected mean fraction of Type 2 AGN of exactly 50%. This 'tilted disc' picturepredicts reasonable alignment of observed nuclear structures on average, butwith distinct misalignments in individual cases. Initial case studies of thefew well resolved objects show that such misalignments are indeed present.

Misaligned Discs as Obscurers in Active Galaxies