We have constructed a preliminary picture of the phenology of bird species that breed in Washington using three principal sources of information: the Northwest Nest Record Program, museum egg collections, and field notes. Since 1955, the University of Washington Burke Museum (UWBM) has maintained a collection of Nest Record Cards contributed by students, professionals, and amateurs. Nest Record Cards contain basic information about nest site and construction, egg and nestling numbers, and parental behavior. Our files now contain over 12,000 of these cards, principally from Washington but also from Idaho, Oregon, British Columbia, and other areas. In addition, we have extracted breeding records from field notes from as early as 1889, and from many egg sets collected in Washington and now housed at either UWBM, the University of Puget Sound (UPS), the Washington State University Connor Museum (WSU), or the Western Foundation of Vertebrate Zoology (WFVZ). For a few species we have also included data extracted from adult birds collected as museum specimens, provided that the measurements associated with these specimens included accurate estimates of first-egg dates or of clutch size. Project homepage: http://www.burkemuseum.org/ornithology/phenology