This text provides an overview of recent developments and advances in the understanding of the role of clouds in climate and atmospheric chemistry. Topics covered include the modelling of clouds in GCMs; observations of the microphysical properties of clouds; the water vapour cycle; troposphere/stratosphere exchange; the role of clouds in tropospheric ozone; the regulation of current and paleoclimate by clouds; radiative/convection interactions; anthropogenic sulphate aerosols; and the modification of cloud properties.