BACKGROUND AND PURPOSE: The lumbar zygapophyseal joints (LZJs) are thought to be a source of low back pain (LBP); however, no valid or reliable indicators exist. The purpose of this study was to obtain a consensus from an expert panel on the indicators of LZJ pain. SUBJECTS: A multidisciplinary panel of 20 experts in the field of LBP participated in this study. METHODS: A 3-round Delphi survey designed to obtain a consensus on the indicators of LZJ pain was completed by use of accepted protocols. Subjects also were asked to justify their selection of each indicator. RESULTS: Following the 3 rounds, consensus was achieved, and 12 indicators were identified. Those that reached the highest levels of consensus were a positive response to facet joint injection, localized unilateral LBP, positive medial branch block, pain upon unilateral palpation of the LZJ or transverse process, lack of radicular features, pain eased by flexion, and pain, if referred, located above the knee. Justifications for the experts' selection of the indicators, predominantly based on pathoanatomical mechanisms, also were described. DISCUSSION AND CONCLUSION: This Delphi survey identified 12 indicators of LZJ pain, each with an associated pathoanatomical mechanism justifying selection. This survey provides preliminary validation for these indicators, which will be of value in further research into the classification and treatment of LZJ pain.