Large wildland fires in conifer forests typically involve some degree of crowning, with their initiation and propagation dependent upon several characteristics of the canopy fuels. Recent outbreaks of mountain pine beetle (Dendroctonus ponderosae Hopkins) in lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) forests and spruce beetle (Dendroctonus rufipennis Kirby) in Engelmann spruce (Picea engelmannii Parry ex Engelm.) forests have affected vast areas across western and northern North America, which have subsequently produced forests containing relatively large amounts of dead or "bark beetle-altered" canopy fuel. Given that the transition to crowning represents an important threshold in terms of large fire growth and wildland firefighter safety and effectiveness, a better understanding of the potential role of bark beetle-altered foliage in altering crown fire initiation and spread is needed. This paper summarizes a recently completed research project dealing with the measurement and characterization of the changes in crown fuel flammability caused by recent bark beetle attacks and consequently the implications of these changes on crown fire potential in these affected forest types.