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This paper provides an overview of Canadian research on snow, frozen soils and permafrost hydrology during the years 1995-98. There were significant advances in the understanding of processes and the development of models of snow accumulation and melt, including the relocation of snow by wind, snow interception in forest canopies, sublimation and energy balance during snowmelt. A major aspect was the development of physically based predictive techniques that account for the effects of heterogeneous topography, vegetation and snow properties, and complex boundary-layer development on snow accumulation, evaporation, melt and runoff. Another advancement is in the linkage of physical snow processes with chemical models to better describe ion accumulation and elution from snow. Snow ecology has shown the interactions in nutrient cycles that involve snow. Frozen ground research has resulted in significantly improved models of frozen soil infiltration, based on both field observations and thermodynamic principles. Research in permafrost regions includes the exfiltration of groundwater in the seasonally thawed zone and the occurrence of perennial springs discharged from below the permafrost. Groundwater discharge is important to features such as icings and the occurrence of wetlands in a polar desert. Processes governing runoff generation on hillslopes have been examined, both in continuous and discontinuous permafrost zones. In terms of future research directions, consideration should be given to continued intensive field studies of cold region hydrological processes and the incorporation of these processes into aquatic chemistry and hydrological models and land surface schemes used in atmospheric models. A better understanding of the role of hydrological boundaries in affecting the rates of processes is needed. The question of scaling processes up from the small scale at which they are relatively well understood, to the larger scales necessary to address global environmental concerns also should be addressed. Copyright (C) 2000 John Wiley & Sons, Ltd.