IOCV is pleased to present “Citrus Rootstocks: Their Characters and Reactions”, an unpublished manuscript by the late Prof. W.P. Bitters, University of California, Riverside. Based upon Prof. Bitters research and many other sources, this work was compiled between the late 1960’s and 1986 (additional information in preface). It represents a comprehensive (for that era) treatment of many facets of citrus rootstock physiology, horticulture, and pathology. Rootstocks serve as both conduits for citrus disease development and potential disease management tools, as well as tools in dealing with abiotic stresses. The history of the use of rootstocks for citrus has largely been determined by these factors, and they continue to greatly influence citrus rootstock research and usage. Although many advances in knowledge regarding citrus rootstocks have been made since 1986, the basic information presented remains important for all citriculturists. We hope that this Special Topic in IOCV’s Journal of Citrus Pathology makes this valuable resource more widely available.