MEDICAL SCIENCES. For the article “Community assembly and invasion: An experimental test of neutral versus niche processes,” by Joseph Fargione, Cynthia S. Brown, and David Tilman, which appeared in issue 15, July 22, 2003, of Proc. Natl. Acad. Sci. USA (100, 8916–8920; first published July 3, 2003; 10.1073/pnas.1033107100), the authors note that in line 13 of the abstract, the phrase “which occurred at lower species richness” should read “which occurred at higher species richness.”