Two new methods for distinguishing two-dimensional (2D) turbulence from slab turbulence are applied to Helios magnetometer data. Two-component models with varying slab and 2D ingredients are considered. Both methods indicate that solar wind magnetic turbulence possesses a dominant (~85% by energy) 2D component. The presence of such a large 2D component provides a natural solution to the long-standing problem of ''too small'' cosmic ray mean free paths derived from quasilinear scattering theory when using the slab model. ¿ American Geophysical Union 1996