Kroetsch, D. J., Geng, X., Chang, S. X. and Saurette, D. D. 2011. Organic soils of Canada:Part 1. Wetland Organic soils. Can. J. Soil Sci. 91: 807-822. In the Canadian System of Soil Classification, the Organic order represents those soils that have developed from materials that are comprised primarily of plant tissue remains and includes both wetland Organic soils and upland Organic soils. This review focuses on the first group; the latter group is discussed in Fox and Tarnocai (2011). Wetland Organic soils can be subdivided into three great groups: Fibrisol, Mesisol, and Humisol, reflecting the degree of decomposition of organic material and the vertical arrangement of different organic horizons and other horizons. Wetland Organic soils are present in all regions of Canada and are commonly referred to as (unfrozen) peatland soils. Unfrozen peatlands with Organic soils cover approximately 75 5568 km² (8.4%) of the land area of Canada. The two primary processes of formation of wetland Organic soils are paludification and terrestrialization. The major taxonomic issues identified for the wetland Organic soils concerns the lack of taxonomic protocols for limnic materials within the soil control section. This is an issue for those soil profiles in which the middle tier is dominated by, if not entirely composed of, deposited limnic materials. Further work is required to determine if these issues should be expressed at the great group or subgroup level of classification. Our understanding of the effects of management practices such as cultivation, tree removal, drainage, and peat extraction on soil properties needs to be translated into models of soil development.