Correction for "Regulation of T cell activation, anxiety, and male aggression by RGS2," by Antonio J. Oliveira-dos-Santos, Goichi Matsumoto, Bryan E. Snow, Donglin Bai, Frank P. Houston, Ian Q. Whishaw, Sanjeev Mariathasan, Takehiko Sasaki, Andrew Wakeham, Pamela S. Ohashi, John C. Roder, Carol A. Barnes, David P. Siderovski, and Josef M. Penninger, which was first published October 10, 2000; 10.1073/pnas.220414397 (Proc. Natl. Acad. Sci. U.S.A. 97, 12272-12277). The authors note, "Fig. 2 contains a mistake in panel A as the CD4/CD8 scatterplots for rgs2 and rgs2-/- mice were duplicated when preparing the figure for publication. Multiple independent experiments showed and confirmed that there is no difference between the groups in the thymocyte populations. Therefore none of the conclusions of the paper are affected. We have included a new set of graphs for Fig 2A from an independent experiment performed concurrently with that in the published paper. We apologize for the oversight in preparing the original figure." The revised figure and its legend appear below. (figure presented).