I analyzed the distribution and abundance of wintering shorebirds (Scolopacidae, Charadriidae, and Recurvirostridae) in Tomales Bay, California, on the basis of 57 baywide counts conducted over 10 years, from 1989-90 to 1998-99. Tomales Bay supports up to 20,689 shorebirds in early winter, thus qualifying as a wetland of "regional" importance in the Western Hemisphere Shorebird Reserve Network. Minimum overall shorebird abundance fell as low as 1291 in late winter. Tomales Bay supported approximately a third of the wintering shorebirds in the Point Reyes/Bodega Bay area in early winter.