An adjustable orthopedic back support includes a posterior panel assembly, a circumferential rail strap having ends attached to the posterior panel assembly, and at least one selectively positioned anterior panel assembly. The rail strap has an unattached intermediate length extending between its attached ends. The anterior panel assembly is carried on the unattached intermediate length of the rail strap, and is adapted for sliding linear adjustment along the rail strap relative to the posterior panel assembly. The anterior panel assembly overlaps a portion of the posterior panel assembly, and has a extension portion selectively linearly extending from the posterior panel assembly such that the back support is custom adjusted to circumferentially fit around a lumbar region of the wearer.