Objectives.-The purpose of this paper is to describe the 4-step process (consent, selection, protection, and abstraction) of acquiring a large sample of chiropractic patient records from multiple practices and subsequent data abstraction.Methods.-From April 2017 to December 2017 RAND acquired patient records from 99 chiropractic practices across the United States. The records included patients enrolled in a survey e study (prospective sample) and a random sample of all clinic patients (retrospective sample) with chronic back or neck pain. Clinic staff were trained to collect the sample, scan, and transfer the records We designed an on-line data collection tool for abstraction. Protocols were instituted to protect patient confidentiality. Doctors of chiropractic were selected and trained as abstractors, and a system was established to monitor data collection.Results.-In compliance with data protection protocols, 3,603 patient records were scanned, including 1,475 in the prospective sample and 2,128 in the random sample. A total of 1,716 patients (prospective sample) consented to having their records scanned, but only 1,475 could be retrieved. Of records scanned, 19 percent were unusable due to illegibility, no care during the period of interest, or poor scanning. The abstractor inter-rater reliability for appropriateness of care decisions was fair to moderate (kappa .38-.48).