Biophysics. In the article “Folding and aggregation of designed proteins” by R. A. Broglia, G. Tiana, S. Pasquali, H. E. Roman, and E. Vigezzi, which appeared in number 22, October 27, 1998, of Proc. Natl. Acad. Sci. USA (95, 12930–12933), the following correction should be noted. In Fig. 1b, the designed sequence of amino acids S₃₆ contains a typographical error in that only 35 of its 36 monomers appear. The missing amino acid is of type R and should be located between amino acids E (sixth) and G (seventh). The correct sequence is:S₃₆ = SQKWLERGATRIADGDLPVNGTYFSCKIMENVHPLA. Although this typographical error does not change the results presented in the paper because they were obtained with the correct number and sequence of amino acids, it constitutes a nuisance for anybody interested in reproducing our results, and we apologize for the inconvenience. We want to thank Prof. H. S. Chan, of the University of Toronto, for calling our attention to this error.