  The galactic black hole binary systems give an observational template showing
how the accretion flow changes as a function of increasing mass accretion rate,
or L/L_Edd. These data can be synthetised with theoretical models of the
accretion flow to give a coherent picture of accretion in strong gravity, in
which the major hard-soft spectral transition is triggered by a change in the
nature and geometry of the inner accretion flow from a hot, optically thin
plasma to a cool, optically thick accretion disc. However, a straightforward
application of these models to AGN gives clear discrepancies in overall
spectral shape. Either the underlying accretion model is wrong, despite its
success in describing the Galactic systems and/or there is additional physics
which breaks the simple scaling from stellar to supermassive black holes.
