We studied the nesting ecology of Winter Wrens (Troglodytes troglodytes) from 1994–1996 in coastal, coniferous, temperate rain forest of southeastern Alaska. Overall nesting success (estimated by the Mayfield method) of 143 nests exceeded that reported for other published studies of temperate wrens, including T. troglodytes. Wrens used understory nest sites (logs, stumps, root disks of uprooted trees, understory moss, stream banks) in two forest sites where predation of nests was low (2% of 65 nests). Males at these two sites commonly had small territories (1.8 ha ± 0.3 SE and 1.2 ha ± 0.1 SE) and often mated polygynously (22% and 78% of males had at least two mates). In the third study area, where predation (probably by red squirrels, Tamiasciurus hudsonicus) on understory nests was relatively high (19% of 59 nests), nests most often were placed in moss clumps on tree branches, as high as 18 m above ground. Males in this study area had the largest territories (2.8 ha ± 0.4 SE) and most (90%) mated monogamously. Variation in nesting ecology among these three superficially similar (mature conifer forest) sites may be related to subtle differences in habitat features and predator abundance.