The latitude dependence of the field line-averaged pitch angle diffusion coefficient of 1-MeV protons in the magnetosphere has been calculated under the following assumptions: Scattering is due to gyroresonant interaction with a broad band spectrum of ion cyclotron waves, and the magnetospheric magnetic field model includes the internal dipole and the external solar wind compression as well as night side current sheet effects. In addition, calculations were performed in a model which simulates geomagnetic storm time ring currents. It could be shown that the power levels of normal quiet time magnetospheric wave activity are not sufficient to cause strong pitch angle scattering but that this situation may change during geomagnetic storms, as has indeed been observed. By using the field line-averaged pitch angle diffusion coefficient the associated radial diffusion coefficent &kgr;⊥ (either through gyroresonant interaction or through shell splitting) was calculated. It was shown that &kgr;⊥ was too small in the pseudotrapping region to compete with direct particle access and that it yielded values comparable with previous estimates due to other processes in the high-latitude closed drift shell region. In contrast to these other estimates, which involved sudden impluses and sudden commencements to provide the magnetic fluctuations, the wave-particle interaction picture developed here implies a steady radial diffusion at all times, temporal enhancements occurring during geomagnetically disturbed times.