This project supports an open community workshop addressing organic speciation within ambient atmospheric aerosols. Although it is understood organics in the aerosol phase probably play important roles with respect to human health and/or climate, there remains considerable uncertainty as to the nature and specific contributions of such effects. This workshop will evaluate the state of the science, identify gaps in present understanding and reach community consensus on current research needs and future direction. The workshop will have a broader impact on the scientific community with respect to producing a summary document dealing substantively with an important interdisciplinary area of atmospheric science. Under support from this award a number of graduate students and junior postdoctoral fellows from U.S. institutions will significantly enhance their professional development by participation in the meeting.