Recent measurements of the charge states of low-energy (~100 keV/nucleon) solar cosmic rays at 1 AU are discussed. The measurements are consistent with models involving charge equilibrium with neutral matter at the sun only if the particles lose ~90% of their energy owing to adiabatic deceleration in the solar wind. Such an energy loss is shown to be possible only if the diffusion coefficient for 1-MeV/nucleon particles is smaller than 1020 cm2 s-1. The implications of these results for models of solar cosmic ray acceleration are discussed.