This NIJ Report evaluates a test protocol for explosives trace detectors and describes a nonspecialist's model test experience. The test protocol was applied to a single instrument representative of commercially available trace detectors to identify flaws or pragmatic barriers to the application of the test protocol contained in NIJ Guide 100-99. A key objective of Evaluation of a Test Protocol for Explosives Trace Detectors Using a Representative Commercial Analyzer (NIJ Report 100-99) was to determine whether the proposed methods were realistic, clearly presented, and technically sound. Other objectives include modification of the test protocol with corrections or deletions based on laboratory experiences and descriptions or documentation of actual findings from laboratory testing.