Nest success and nest-site characteristics of the Tufted Duck (Aythya fuligula) were studied during the 1996 breeding season at Loch Leven, Scotland. Approximately 463 ± 47 Tufted Duck pairs nested in association with 6,674 ± 805 Black-headed Gull pairs (Larus ridibundus) on St. Serf's Island. Tufted Ducks had an apparent nest success rate of 79.5% (Range: 65.8%–83.6%; n = 73). Multiple logistic regression was used to test the hypothesis that nest-site characteristics, such as distance to colony edge, overhead and vertical nest cover and distance to nearest Tufted Duck or Black-headed Gull nest, affect nest success. By using only the Tufted Duck nests with a known fate (n = 60), distance to the colony edge was identified as the primary predictor of nest success (P = 0.004), with successful nests (31.60 ± 1.71 m) located farther from the colony edge than those that failed (18.75 ± 2.61 m). Results support the central-periphery nest distribution model which suggests that nests located in the center of a colony, particularly in homogeneous habitats, are less accessible to predators and have greater reproductive success.