Knowledge of forest biomass is necessary for reporting on the state of Canada's forests. It is also an indicator of carbon that enables insights on the interaction between forests and the atmosphere. Forest biomass information has largely been aspatial and derived using plot estimates from Canada's National Forest Inventory. Provincial and territorial governments and private industrial organizations have broadened the diversity of information needs and demand for methods that are more spatially explicit. These realities have resulted in a variety of data sources nested within four approaches that can be applied from local to national scales. Earth observation data contribute to each of these approaches to varying degrees and not all approaches result in large area biomass maps. This paper describes the approaches for biomass mapping in Canada, their synergism, and highlights their dynamic nature as new data sources and ongoing developments will continue to refine these approaches to estimate, map, and monitor forest biomass in Canada.