In recent years, there has been an increased awareness of materials-related distress (MRD) in portland cement concrete pavements. This research presents a protocol for identifying possible causes of MRD. The protocol is part of a series of guidelines prepared for the detection, analysis, and treatment of MRD in concrete pavements. The guidelines have been applied to a number of pavements, and the result of one study is presented. Laboratory results indicate that the subject pavement experienced a number of possible distress mechanisms and that no clear single cause exists. The guidelines were found to be useful in steering analyses without stopping at the first distress mechanism identified, thereby allowing for examination of all other possibilities. The guidelines will be most useful to engineers trying to correlate visual assessment and performance with the results of laboratory analyses.