We report the first observation of double brooding by Black-bellied Whistling-Ducks (Dendrocygna autumnalis). We monitored 151 nest boxes on the Rob and Bessie Welder Wildlife Refuge in south Texas during 1998 and 1999 and uniquely marked all incubating pairs of Black-bellied Whistling-Ducks using these nesting structures. We color-banded a pair of Black-bellied Whistling-Ducks in May 1999 that was incubating a clutch of 21 eggs, from which 18 young eventually fledged. The same pair later incubated a second clutch of 15 eggs in July and August 1999, of which 12 hatched. Double brooding is apparently not a common reproductive strategy for Black-bellied Whistling-Ducks in south Texas, but could be facilitated through biparental investment in most aspects of reproduction, including incubation and brood rearing, and a relatively long potential breeding season in most of this species' breeding range.