The interactions of aerosol particles with cloud structures continue to cause significant uncertainties in the radiative balance of the atmosphere and several aspects of precipitation. There are a number of open questions relating to the chemistry of aerosol-cloud interactions for both warm clouds and ice clouds. Many of these questions involve both chemistry and microphysics. Topics will include both the aqueous chemistry in cloud droplets and the microphysics of the activation and scavenging process. Findings from field, laboratory, and modelling studies will be included. This workshop will include 24 talks, including 12 held jointly with the organic aerosol workshop.