Many transportation agencies have begun to introduce explicit transportation system performance measures into their policy, planning, and programming activities. Performance measurement is being applied widely in many transportation agencies and often extends well beyond the performance of the transportation system itself. The first section of this conference resource paper is a definition of the elements of the process necessary to use performance measures to influence decisions and a summary of why agencies are increasingly interested in the use of system performance measures as a decision-making tool. Subsequent sections define several decision-making contexts with which performance measures may be applied and present some general lessons learned in working with a broad range of agencies that have begun to implement some aspect of performance-based planning and decision-making processes. Finally, some case study examples are provided to illustrate particular findings, and overall conclusions are presented.