Using a multiple-core paleoecological approach, we studied the development of a small kettle-hole wetland (informal name Spiraea wetland) in southern Ontario. The sedimentary record begins at around 11 700 BP, when Picea and herbs characteristic of a disturbed environment were the principal components of the upland vegetation. These were replaced by ca. 9500 BP by Pinus dominance, which persisted until at least 6300 BP. Mixed deciduous forest communities then developed and were only disturbed by Euro-Canadian settlement in the last few hundred years. Initially, the basin contained an open lake, which was progressively colonized by a range of aquatic plants, becoming a shallow open water wetland community by 9500 BP. A marsh community spread rapidly from the edge of the basin, and a mat of aquatic mosses filled the central area of open water before marsh vegetation became established there. Between 6300 and 1500 BP, there is a marked decrease in sedimentation rates, and the paleoecological data imply that the vegetation communities at the coring points varied between marsh, shrub swamp, and conditions where no net sediment accumulation occurred. Sedimentation rates increased in the upper part of the core, as the modern tall-shrub swamp developed.