The 50-year evolutionary development of the current Manual on Uniform Traffic Control Devices (MUTCD) has resulted in many traffic control device standards that are based on subjective opinion. As vehicle design, the driver population, and society's demand for a safer highway system change, many of these traffic control device standards need reexamination. A research study was conducted to identify those MUTCD standards that (a) lack a research basis, or are in conflict with research findings, and (b) would likely benefit from research and scientific investigation. Nearly all MUTCD standards were evaluated. Identification of those MUTCD standards having the greatest need for additional research was achieved through (a) evaluation of selected MUTCD standards by the project team and a panel of traffic engineering practitioners, and (b) evaluation of relevant previous traffic control device research. Seventeen MUTCD standards were identified as having a significant need for additional research. Eight areas were recommended as having high priority for future traffic control device research. To provide a tool for future research and to serve as an aid to ongoing development of the MUTCD, a computerized data base management system was created. It includes documentation of previous traffic control device research as it relates to each standard within the MUTCD.