This book presents some of the history of the growth, impact, broadening of responsibility, and implementation of entomology in U.S. organisations and its expansion into research, education, extension and regulatory functions. The more than 150-year existence of Federal entomology is paved with accomplishment and outstanding scientific leadership. Entomology in the Federal establishment began before the U.S. Department of Agriculture (USDA) was formed. Major emphasis in this publication is placed on the transition of entomological research and other entomology programs in Federal government organisations beginning with the first Patent Office entomologist to the present multidisciplinary structure of ARS. Regulatory, quarantine, co-operative Federal/State/extramural, and other programs that have branched off from the original entomological organisation or developed independently are also discussed within the limits of access to available information.