Satellite and airborne measurements of reflected sunlight are often used to estimate aerosol and cloud properties. Current methods for interpreting these observations consider radiative transfer a predominantly vertical, one-dimensional process; they ignore the fact that nearby areas can influence each other's brightness through three-dimensional interactions such as shadowing or diffusion of light. Theoretical simulations have long suggested that three-dimensional processes can cause considerable uncertainties in estimated cloud and aerosol properties. This presentation will review some observational evidence for three-dimensional radiative effects not considered in current data interpretation method, and will discuss the implications for aerosol and cloud remote sensing. Subsequently, it will outline some possible approaches for reducing the uncertainties caused by 3D radiative effects. Finally, it will describe multi-view cloud lidars?a new set of instruments for which 3D radiative effects are not a source of uncertainty, but a source of new information on cloud structure.