OBJECTIVES: To develop a patient-reported outcome (PRO) measure to assess the key symptoms of chronic low back pain (cLBP) through qualitative concept elicitation (CE) and cognitive interviews. METHODS: Adult patients (18-80 years) with clinical diagnoses of cLBP of non-malignant origin and current pain scores ≥4 on a 0-10 numerical rating scale (NRS) were recruited in the U.S., UK, and Germany.  Trained interviewers conducted CE and cognitive interview sessions with participating patients using semi-structured interview guides.  The CE interviews elicited spontaneous reports of symptom experiences followed by probing to further explore and confirm concepts.  The cognitive interviews evaluated the degree of patient comprehension of the items in the draft PRO measure.  All interview sessions were audio recorded and transcribed.  The CE interviews were coded for qualitative content analysis using Atlas.ti, and the cognitive interview transcripts were summarized in cognitive report tables. RESULTS: Forty-three CE interviews were conducted (mean age: 48.6±13.0, 53.5% female, 74.4% -White/Caucasian).  Mean pain NRS score was 6.7± 1.3.  A total of 1342 symptom codes were derived from the transcripts, representing 32 different symptom concepts.  Data from CE interviews was considered alongside existing measures, published literature and expert opinion to develop a 23-item draft measure.  Thirty additional patients participated in four waves of cognitive interviews, during which nine items were removed and others were substantially modified to create the Pain Assessment for Low Back Symptoms (PAL-S). CONCLUSIONS: The PAL-S is a 14-item PRO measure for assessing symptoms of cLBP that has been developed through direct qualitative patient involvement in accordance with the FDA’s PRO Guidance and scientific best practices.  Cognitive interviews have provided evidence from patients that the measure is comprehensive, relevant to their cLBP experience, comprehendible, and easy to complete.  The measure will be further tested in additional qualitative and quantitative studies to evaluate its measurement properties.