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Low reproductive success is thought to be a chief cause of the steady decline in numbers of piping plover (Charadrius melodus) that nest in the northern Great Plains. Surprisingly, few reproductive success data are published from alkali lakes in the region, where most breeding pairs of piping plover nest. During 1994 to 1997 we measured nest success and fledging rates of piping plovers at 32 alkali lakes across northwestern North Dakota and northeastern Montana, at the center of the species' breeding range in the Great Plains. Annual nest success and fledging rates averaged 38% (Mayfield estimate; 20 to 66 nests/year) and 0.76 chicks/pair (28 to 76 pairs/year). The mean annual fledging rate we observed approximated that previously projected for the region from a small number of major breeding areas, and was at least 33% below estimated levels needed for population stability. About one-half of the productivity losses occurred during the egg stage, especially near hatching. Our data confirm that reproductive success of piping plovers on alkali lakes probably is less than that needed to sustain the species' Great Plains population.