The Guide for Physical Therapist Practice states that the physical therapist determines the expected outcomes for each intervention and engages in outcomes data collection and analysis. Outcomes tracking provides a systematic way for therapists to monitor treatment effectiveness and efficiency. A familiarity with outcome measures for the patient with low back pain is indispensable for therapists in the outpatient orthopaedic setting, where patients with lumbar pain often comprise the majority of the caseload. The therapist must be able to evaluate and choose appropriate measurement tools and understand the clinical meaning of measurements to successfully employ these instruments. The purpose of this article is to review measurement instruments for patients with low back pain and to offer practical guidelines for selection and use of outcome measures for this population. The reliability, validity, sensitivity to change, and utility of common outcome measures are discussed. An overview of generic, disease-specific, and patient-specific tools is provided with specific commentary on the use of the SF-36, SF-12, Oswestry Questionnaire, Roland-Morris Questionnaire, and patient-specific tools. Practical guidelines for utilizing outcome measures in clinical practice and the overall benefits of outcomes tracking are highlighted.