The purpose of the current report is to describe the classification, treatment, and outcomes of a patient with lumbar extension syndrome. The patient was a 40-year-old female with an 18-month history of mechanical low back pain (LBP). The patient reported a history of daily, intermittent pain (mean intensity of 9/10) that limited her ability to sit, stand, walk, and sleep, as well as perform work-related activities. Symptom-provoking movement and alignment impairments associated with the direction of lumbar extension were identified and modification of these impairments consistently resulted in a decrease in pain. Treatment was provided in 3 sessions over a 2-month period. Priority of treatment was to train the patient to restrict lumbar extension-related alignments and movements during symptom-provoking functional activities. Exercises to address the extension-related impairments also were prescribed. The primary change in outcome was a decrease in the mean intensity (2 months: 2/10; 6 months: 1/10) and frequency of pain (2 months: decreased pain with standing and walking; 6 months: additional decrease with sitting, standing and walking). She also reported a decreased duration and number of LBP episodes. Classification directed treatment resulted in improvement in short and long term impairment and functional-level outcomes.