Performance measures are sets of defined, outcome-based conditions or response times that are used to evaluate success. Performance measures focus on what to achieve, not how to achieve it. The purpose of this guidance booklet is to introduce the concept of performance measures and performance data collection for work zone safety. The booklet defines performance measures; discusses the rationale for using performance measures for work zone safety; provides a process and test for developing good performance measures; provides sample performance measures for work zones; discusses when and how to measure performance, including types of data and data collection techniques, and what to do with the resulting data; provides real world lessons learned; and provides guidance on where to go for more information.