PAG thanks Gabriel Acebo for moral and financial support for almost most years of bluebird studies in South Carolina. We thank Rene Colorada and Lloyd Kiff for providing measurements of eggs from the Western Foundation of Vertebrate Zoology; Sylvia Halkin for recordings of songs and Tu-a-wee calls, and for continued discussions about vocal communication; Sandy Gaunt for providing sonograms; and the managers of Clemson University and the University of Georgia for access to field sites. Generous "Acebo-grants," NIMH grants (RO1 MH55198-01A1), and NSF grants (IBN-9222005, BNS-8919822, BSR-8417500, and VPW-82) provided financial support. An Independent Scientist Research Award (NIMH, KO2 MH00706-06) partly supported PAG during the writing of the first version. We thank Eastern Bluebird watchers everywhere, but especially B. C. Pinkowski, David Pitts, R. C. Krieg, and Gary Richison, whose remarkably careful and informative contributions to bluebirdology have enriched our own. We thank readers whose suggestions made us clearer: Cathy Carver, Brook Vinnedge, Melanie Rathburne, Judy Guinan, Jill Goldstein, Jason Lang. We thank Bob Chandler for locating references on fossil bluebirds; and L. Bevier, Keith Russell, Don Kroodsma, Bill Read, and J. Zickefoose for formal comments. Finally, we thank the individual Eastern Bluebirds that we have been privileged to observe.