Aerosol-cloud interactions are considered as one of the largest uncertainties in the estimate of climate forcing by human activities. While numerical mechanisms and processes associated with aerosol-cloud interactions have been proposed, their climate significance ultimately has to be assessed from a radiative energy point of view. This session seeks presentations reporting progress in understanding the change of cloud radiative properties and radiative effects as a result of aerosol impact on cloud microphysics and lifetime, change of aerosol radiative effects by surrounding (and underlying) clouds, and novel measurement and modeling techniques to quantify the impacts of aerosol-cloud interactions on radiation.