Beyond the  implementation, we would like to thank the many people who worked on the  Scheme standard, including William Clinger and Jonathan Rees, who edited the R4RS, and Chris Haynes, David Bartley, Chris Hanson, and Jim Miller, who prepared the  standard. Dan Friedman has been a long-time leader of the Scheme commu- nity. e community’s broader work goes beyond issues of language design to encompass significant educational innovations, such as the high-school curriculum based on EdScheme by Schemer’s Inc., and the wonderful books by Mike Eisenberg and by Brian Harvey and Mahew Wright. We appreciate the work of those who contributed to making this a real book, especially Terry Ehling, Larry Cohen, and Paul Bethge at the  Press. Ella Mazel found the wonderful cover image. For the second edition we are particularly grateful to Bernard and Ella Mazel for help with the book design, and to David Jones, TEX wizard extraordinaire. We also are indebted to those readers who made penetrating comments on the new dra: Jacob Katzenelson, Hardy Mayer, Jim Miller, and es- pecially Brian Harvey, who did unto this book as Julie did unto his book Simply Scheme. Finally, we would like to acknowledge the support of the organiza- tions that have encouraged this work over the years, including support from Hewle-Packard, made possible by Ira Goldstein and Joel Birn- baum, and support from , made possible by Bob Kahn. xxviii