This lecture provides an introduction to McKenzie Method® of Mechanical Diagnosis and Therapy® (MDT), a system of assessment, classification, treatment & prevention of musculoskeletal disorders that is safe, reliable, valid, and predictive and evidence based. The assessment incorporates repeated test movements in various planes and static positions to determine the direction in which a patient needs to move and with how much force to begin (based on centralization of symptoms and changes to obstructed movement). This can be especially important to a chiropractor as it not only helps improve safety but it can also help validate the direction of the adjustment. By determining a directional preference, there is a greater likelihood that a patient's pain will reduce in a short time period. This can allow a chiropractor to introduce active care rehabilitation earlier in the patient's treatment, which can demonstrate even further value to third party payers.