In the boreal forests of North America, fire is the keystone ecosystem process that organizes the physical and biological attributes of the biome over most of its range. Boreal forest ecosystem structure and function are described in terms of the adaptations evolved in response to the periodic occurrence of fire. Recognition of the role of fire as an ecosystem process in boreal regions has resulted in its use in contemporary Canadian forestry practice and ecosystem maintenance and restoration. Examples are provided showing how wildfire and prescribed fire affect the substrate (e.g., soil temperature) and ecosystem processes (e.g., decomposition, soil respiration, and nutrient use efficiency of tree seedlings). Application of a natural disturbance paradigm to boreal forest ecosystem management in Canada is presented, pointing out the challenges and opportunities to research and operational practice.