The Mottled Duck (Anas fulvigula) is a range-restricted species endemic to the western Gulf Coast states and peninsular Florida. As a year-round resident, it relies on coastal marsh and nearby upland habitat during the breeding season. All previous breeding research on Mottled Ducks has observed them nesting in upland habitat such as prairie, rice fields, pastures, levees, dredge-spoil islands, or dry marsh. Here, we report on the first documented cases of overwater nesting for this species. We located 2 transmitter-marked Mottled Ducks nesting in freshwater marsh on an elevated platform constructed of cutgrass, with a water depth >10 cm surrounding the nest. Existing conservation and management plans for nesting Mottled Ducks emphasize protection of upland habitat, but our results suggest that broadening the scope of habitat types assumed to be suitable for nesting Mottled Ducks may be warranted.