This project supports a workshop that is designed to reach out to a broad scientific community of aerosol scientists on issues associated with carbonaceous aerosols in the atmosphere. Considerable controversy exists among aerosol scientists regarding terminology and methodology for measuring and reporting carbonaceous fractions of atmospheric aerosol. This workshop will help to develop a consensus on terminology for carbonaceous aerosol (e.g. the definition of black carbon), address carbon aerosol sampling difficulties, and recommend standardized analysis for carbonaceous aerosol for the purposes of sample intercomparison between field campaigns and longer-term measurement sites.