Mitigation wetlands are constructed to replace anthropologically altered or damaged wetlands. Guidelines have been established to aid in the creation of mitigation wetlands, however, the success of mitigation wetlands has been criticized. Recent studies have demonstrated a lack of in-kind mitigation wetlands. To properly address the functional success of mitigation wetlands, the role of soil and organic matter within wetland environments needs both consideration and further study. This study compares the chemical composition, N and P leaching, nutrient removal, and sorption potential of the two commercial composts to that of three naturally occurring organic wetland soils. These properties are critical to understanding and replicating the functions of natural wetlands. Such a comparison allows for the evaluation of composts as an organic amendment in freshwater wetland mitigation. Two commercially available composts (Agresoil Leaf Compost and Coast of Maine Quoddy Blend Lobster Compost) and three organic wetland soils (a muck, a Sphagnum peat and a Carex peat) were utilized in the study. Several experiments were conducted to determine the ability of the various organic materials to supply nutrients for plant growth and to sequester nonpoint source pollutants such as herbicides, heavy metals, and nutrients. The materials were also evaluated for their potential to release excess nutrients into the aquatic environment. The organic materials were characterized for nutrient levels (both total an exchangeable), pH, cation exchange capacity, percent organic matter, C:N ratio, percent aliphatic and aromatic carbon, polarity, and functional groups. Significant differences were measured for several important properties including total N, total P, extractable P, pH, and percent organic matter. Both commercial composts had significantly higher levels of Total P as compared to the organic wetland soils. Total P levels were 2454 mg kg^-1 and 2410 mg kg^-1 for the Leaf Compost and the Lobster Compost, respectively. Both commercial composts had significantly higher levels of Morgan's extractable P levels as compared to the organic wetland soils. Extractable P levels were 130.6 mg kg^-1 and 89.99 mg kg^-1 for the Leaf Compost and Lobster Compost, respectively. Leaching experiments were conducted to evaluate the different organic materials as potential nutrient loading sources, specifically N and P which are limiting nutrients that can contribute to the eutrophication. Phosphorus leaching was measured under aerobic, anaerobic, and saturated conditions. Under all redox conditions, the commercially available composts had significantly higher levels of SRP as compared to the organic wetland soils. For all samples, the release of SRP increased with the duration of the saturation period. Initial studies indicate that the utilization of compost as an organic amendment in mitigation wetlands could result in an increase in nutrient release into aquatic environments. Specifically, a first flush phenomena was observed after composts were saturated for 24 hours. Significantly higher levels of nitrate-nitrogen were released from the compost as compared to the organic wetland soils. Mean nitrate levels released after 24 hours were 40.6 mg kg^-1, 3.8 mg kg^-1, 0.6 mg kg^-1, 0.67 mg kg^-1, and 0.00 mg kg^-1, for the Leaf Compost, Lobster Compost, muck, Carex peat, and Sphagnum peat, respectively. As the saturation period increased, the release of nitrate-nitrogen decreased significantly. This decrease in nitrate-nitrogen is most likely due to an increase in denitrification, which occurs under anaerobic conditions. Currently, batch equilibrium sorption experiments are being performed to determine the sorption potential of three different substances: 2,4-D, phosphorus (KH₂PO₄); and lead (Pb).