Because they treat relatively benign source waters, most treatment marshes may also be regarded as wetland restoration projects. Indeed, the large phosphorus removal marshes in south Florida are a major part of the “Restoration Strategies” initiative designed to improve water quality reaching the remnant Everglades. When wetlands are used to reduce pollutant concentrations and peak stormwater flows, ecological benefits can be achieved. This chapter summarizes those benefits of wetlands used for pollution control and recommends design features to optimize these benefits. The primary objective of most wetland pollution control projects is water quality enhancement, through assimilation and transformation of sediments, nutrients, and toxic chemicals. Secondary benefits that can be incorporated in wetland treatment designs include (1) vegetative biodiversity, (2) protection and production of fauna, and (3) aesthetic, recreational, commercial, and educational human uses. Full realization of these benefits usually requires extra land and extra expenditures.