Adjoint models provide a unique means of characterizing the relationship between distributions of atmospheric pollutants and their sources. This talk will present the value of such calculations for inverse modeling and source attribution. Constituents such as aerosols, nitrogen oxides (NOx) and ozone (O3) contribute to degraded environmental conditions throughout many regions of the world. These same species also play important roles in climate change, as their radiative impacts are large enough to either significantly offset or enhance warming caused by carbon dioxide emissions since the preindustrial era. A key factor in developing effective mitigation policies to address these issues is to improve our understanding of the relationship between emissions, the resulting distribution of pollutants in the atmosphere, and subsequent impacts on environmental endpoints. To start with, adjoint modeling is presented in the context of inverse modeling, wherein observations are used to constrain estimates of aerosol (dust, black carbon) and aerosol precursor (NH3) emissions. Next, the application of global and regional adjoint models for source attribution studies is presented. Case studies highlight the benefits of this approach for assessing long-range transport of ozone and the efficiency of aerosol source impacts on radiative forcing and mortality.