The planned International Dust Workshop in September 2008 is the third workshop in a series that is dedicated to understanding uncertainties in climate-relevant properties of soil-derived mineral dust particles, and their impact on the climate system. Due to its atmospheric abundance mineral dust is an important climate factor, but the magnitudes of the various effects of dust on temperatures, hydrological cycle and nutrient delivery to ecosystems are still largely uncertain. The interest in studying properties and effects of this atmospheric constituent has strongly increased in the past decade due to advances in remote sensing and modeling and as result of new data obtained during several recent field studies. The First International Dust Workshop was held in 1999 in Boulder, USA. It highlighted the large uncertainties in the characterization of dust radiative effects. At that time even the sign of the global annual mean of the direct radiative forcing by dust was unclear. This first workshop pointed out various outstanding issues and recommended strategies for future research to constrain related uncertainties. It became clear that main sources of uncertainties resulted from deficiencies in the understanding of physical and chemical processes controlling and being influenced by dust particles, and from the lack of adequate observational data. The Second Dust Workshop held in Paris, France in 2003 assessed progress on the key issues dust sources and emissions, determining dust properties, and improving modeling and measurement capabilities. Both workshops resulted in important publications in special sections of the Journal of Geophysical Research that were published in 2001 and 2005, respectively. Since the last Dust Workshop, several regional field experiments were carried out that aimed at determining dust properties and understanding processes, in particular related to emission and atmospheric dust transformation. These include the SAMUM-1 and DABEX campaigns (together with parts of the AMMA project) in the Sahara and Sahel regions in North Africa, and the ADEC project focusing on the Chinese deserts. The Third Dust Workshop will thus focus on regional specifics of dust and its related impacts, together with implications for regional and global dust modeling. Integration of observations and models has become an important issue both in terms of model validation and data assimilation. The main goal of this dust workshop is a critical review of the state of the field: to evaluate recent progress in dust studies, determine the remaining knowledge gaps, and make recommendations for future work. The workshop consists of several sessions focusing on specific aspects, featuring presentations by invited speakers and one-hour discussions.