A truck bed divider assembly with a horizontal dividing member operably configured to extend and retract longitudinally to directly couple with sidewalls within a truck bed and with a vertical dividing member disposed in a substantially perpendicular orientation with respect to the horizontal dividing member and operably configured to selectively, removably, and lockably couple to the horizontal dividing member with one or more fasteners and to linearly translate on the horizontal dividing member while coupled thereto, thereby enabling organization within the bed of a truck or other vehicle.