The Common Tern Sterna hirundo and the Arctic Tern Sterna paradisaea present a very difficult problem of identification. Observers in California do not have at hand adequate information on the subject. We asked Mr. Vande Weghe for permission to publish in this journal a translation of the part of his paper “La Sterne pierregarin Sterna hirundo et la Sterne arctique Sterna paradisaea. Identification et Passage en Belgique” (Aves 3: 1–5, 1966) that pertains to field identification (the rest of the paper treats the status in Belgium).*