The design of the composite horizontal stabilizer for the B-1 aircraft has evolved after ten years of experience in the design, processing and testing of graphite and boron epoxy structures. A concentrated effort has been made to develop a stabilizer configuration which makes optimum use of graphite and boron materials to obtain a reasonable weight and production cost saving. The procedures used for the design, test data from the major elements, results of the full scale static test and production cost data are presented. The resulting composite structure has demonstrated a weight saving of 15% for the total stabilizer and 21% for the composite box over the exist ing metal configuration. Cost savings of 17% are indicated in production.