Policies to reduce carbon dioxide emissions can yield substantial co-benefits via reduced emissions of co-pollutants such as particulate matter, nitrogen oxides, and air toxics. Valuation studies suggest that these benefits may be comparable in magnitude to the value of reduced carbon emissions. However, co-pollutant intensity (the ratio of co-benefits to carbon dioxide emissions) varies across pollution sources, and so efficient policy design would seek greater emissions reductions where co-benefits are higher. Moreover, because co-pollutant impacts are localized, the distribution of co-benefits raises important issues of equity, particularly with regard to the unintentional income, racial, and geographic disparities that might result from carbon-charge programs, whether they are trading or fee approaches. This paper presents evidence on intersectoral and spatial variations in co-pollutant intensity and discusses options for integrating co-benefits into climate policy to advance the goals of efficiency and equity.