accretion via a disc rather than spherical infall. That is because the main manifestation of luminous embedded sources are their ubiquitous bipolar outflows (Lada 1985). Since these most naturally arise from discs in most viable models this has always been good indirect evidence. Accretion through a disc is also the key to overcoming the radiation pressure in a number of ways. Firstly, the stellar radiation is isotropic and so a disc only intercepts a small fraction of the total luminosity. Secondly, if the infall is concentrated through a thin disc then the effective accretion rate is amplified. Finally, there is likely to be a large self-shielding effect, whereby material can accrete through the mid-plane, whilst the upper layers of the disc take the brunt of the radiative effects.

This was investigated by Nakano (1989) and Jijina & Adams (1996) who showed analytically that non-spherical accretion caused by magnetised collapse or rotation can overcome the radiation pressure for a range of reasonable starting conditions and accretion rates. Yorke & Sonnhalter (2002) performed 2D axisymmetric radiation hydrodynamical simulations on a collapsing cloud in rotation and came to similar conclusions concerning the upper mass limit. They find accretion rates of about $\sim$10$^{-3}$  starting 