I studied nest-site characteristics and habitat relationships for three species of primary cavity-nesting birds -- hairy woodpecker (Picoides villosus), northern flicker (Colaptes auratus), and red-breasted sapsucker (Sphyrapicus ruber) -- over spatially heterogeneous landscapes in managed forests of the Southern Oregon Cascades during 1995 and 1996. The study was conducted on the Diamond Lake Ranger District of the Umpqua National Forest. I found 163 nests -- 68 nests of red-breasted sapsuckers, 63 of northern flickers, and 32 of hairy woodpeckers. I evaluated characteristics of nest trees, habitat within a 0.04-ha circle surrounding nest trees, and the surrounding landscape and compared these to characteristics of randomly selected plots. Analysis revealed statistically significant differences between nest trees and random trees among species. Variables significantly influencing the probability of use of a tree were state of decay, diameter at breast height, and tree top condition (broken or intact). Red-breasted sapsucker nests were associated with large diameter (mean = 80.5 cm) trees with broken tops. Hairy woodpeckers used large diameter (mean = 80.4 cm) trees in decay class 3 for nesting. Northern flickers were associated with large diameter trees (mean = 77.7 cm) with broken tops. I investigated habitat associations at the landscape level using GIS coverages and FRAGSTATS spatial analysis to generate indices quantifying landscape structure for each study site. Higher numbers of woodpecker nests were found in landscapes with lower proportions of mature closed-canopy forest (trees > 53 cm, canopy closure > 40%), and possessing greater overall habitat complexity. I also detected a significant association between all three species of woodpecker and proximity to edge. red-breasted sapsuckers exhibited the most dramatic affinity for edge habitat, choosing to use nest trees located on a habitat edge more often than would be expected if selection was due to chance alone (P < 5 x 10^-9). Nests of northern flickers and hairy woodpeckers were also significantly associated with habitat edges (P < 0.004 and P < 0.04 respectively). When managing for woodpeckers within managed forest landscapes, large snags (> 80 cm) should be retained. Woodpecker needs for nesting habitat may not be met if retained snags do not represent a diversity of decay classes. Snags representing a variety of tree species and decay classes should be left following management activity. Additionally, management plans should incorporate the use of a variety of methods for stand regeneration. Using prescriptions such as shelterwoods, commercial thinning, and partial cuts, overall landscape diversity will increase, enhancing habitat conditions for nesting woodpeckers.