PERSPECTIVE. In the article “Stripe phases in high-temperature superconductors” by V. J. Emery, S. A. Kivelson, and J. M. Tranquada, which appeared in number 16, August 3, 1999, of Proc. Natl. Acad. Sci. USA (96, 8814–8817), the authors request that the following addition be noted. V.J.E. and J.M.T. are supported by Department of Energy Contract DE-AC02-98CH10886, and S.A.K. was supported by National Science Foundation Grant DMR98-08685.