The purpose of this Checklist is to provide a complete up-to-date list of the bird species that have been recorded in the 49 continental United States and Canada. This list includes the native North American breeding species, the regular visitors, the accidentals from other countries that are believed to have strayed here without the direct aid of man, and those introduced species that have become well established and are now a true part of our avifauna. The A.B.A. Checklist will be revised at frequent intervals to keep up with changes in classification and additions to the avifauna. This edition includes a total of 794 species. For details of geographic range and for a complete list of re<;ognized subspecies the reader is referred to the latest (5th) edition of the A. O. U. Check-List of North American Birds, prepared by a committee of the American Ornithologists' Union, 1957, and to the 32nd Supplement published in April 1973 (Auk 90:411-419).