The northern spotted ( Strix occidentalis caurina) uses a wide array of nesting habitat throughout its current range and successfully reproduces in a variety of stand types on the eastern slope of the Pacific Northwest Cascades. The species has the ability to utilize dynamic forest stands that continue to undergo significant changes in tree density, proportion of tree size classes, and tree species composition. Current stand structure and composition reflect the results of timber harvest, reduced fire effects and ongoing successional and stand development processes. In nest stands, multi-layered canopy was more strongly expressed in numbers of both small (< 13 cm DBH) and large (> 41 cm DBH) trees than in unoccupied stands of the same type within the owl neighborhoods. Tree density and the proportion of shade-tolerant tree species have increased significantly in spotted owl nest sites in both dry and wet forests since Eurosettlement. Barring disturbance, further increases in the dominance of shade-tolerant species should occur over time with continual change in nest stand structure and composition. The development of dense forest stands and ‘old-forest structural attributes’ as a result of reduced fire effects could be potential mitigating factors to the loss of old-forest habitat from harvest and should be considered in determining the available owl habitat in the eastern Cascades. However, old-forest structural attributes in dense, overstocked stands are at high fire hazard and should be viewed as transitional until old-forest habitat with improved sustainability becomes available.