Immunology. In the article “Generation of NK1.1⁺ T cell antigen receptor α/β⁺ thymocytes associated with intact thymic structure,” by Ken-ichi Nakagawa, Kazuya Iwabuchi, Kazumasa Ogasawara, Manabu Ato, Masaharu Kajiwara, Hiroki Nishihori, Chikako Iwabuchi, Hiroshi Ishikura, Robert A. Good, and Kazunori Onoé, which appeared in number 6, March 18, 1997, of Proc. Natl. Acad. Sci. USA (94, 2472–2477), the following correction should be noted. On page 2475, the second line of the left column that reads “… were reconstituted with aly/aly BM cells after lethal irradiation” should read “… were reconstituted with aly/+ BM cells after lethal irradiation.”