A method of operating a system for replenishing a retail facility, the system comprising: a plurality of storage shelves at the retail facility, a storage shelf operable to store a plurality of replenishment inventory items; a plurality of display shelves at the retail facility, a display shelf operable to receive one or more replenishment inventory items from a storage shelf; a management module operable to: determine to replenish a display shelf with an inventory item stored by a storage shelf; and coordinate movement of a plurality of mobile drive units to replenish the display shelf with the inventory item at an inventory restocking station; a first mobile drive unit operable to receive first instructions from the management module to transport the display shelf to the inventory restocking station; a second mobile drive unit operable to receive second instructions from the management module to transport the storage shelf to the inventory restocking station; and the inventory restocking station, characterized in that the method comprises: detecting, by the management module, that a display shelf at the retail facility is low on an inventory item and needs to be replenished with an inventory item, wherein the management module determines that an amount of inventory items in a display shelf has fallen below a predetermined threshold; determining, by the management module, that the inventory item is stored in a storage shelf at the retail facility; instructing, by the management module, the first mobile drive unit to transport the display shelf to the inventory restocking station at the retail facility; instructing, by the management module, the second mobile drive unit to transport the storage shelf to the inventory restocking station at the retail facility; wherein the display shelf receives the inventory item at the inventory restocking station; after the inventory item is received by the display shelf at the inventory restocking station, the management module instructing the first mobile drive unit to transport the display shelf to a designated location within the retail facility. a plurality of storage shelves at the retail facility, a storage shelf operable to store a plurality of replenishment inventory items; a plurality of display shelves at the retail facility, a display shelf operable to receive one or more replenishment inventory items from a storage shelf; a management module operable to: determine to replenish a display shelf with an inventory item stored by a storage shelf; and coordinate movement of a plurality of mobile drive units to replenish the display shelf with the inventory item at an inventory restocking station; determine to replenish a display shelf with an inventory item stored by a storage shelf; and coordinate movement of a plurality of mobile drive units to replenish the display shelf with the inventory item at an inventory restocking station; a first mobile drive unit operable to receive first instructions from the management module to transport the display shelf to the inventory restocking station; a second mobile drive unit operable to receive second instructions from the management module to transport the storage shelf to the inventory restocking station; and the inventory restocking station, characterized in that the method comprises: detecting, by the management module, that a display shelf at the retail facility is low on an inventory item and needs to be replenished with an inventory item, wherein the management module determines that an amount of inventory items in a display shelf has fallen below a predetermined threshold; determining, by the management module, that the inventory item is stored in a storage shelf at the retail facility; instructing, by the management module, the first mobile drive unit to transport the display shelf to the inventory restocking station at the retail facility; instructing, by the management module, the second mobile drive unit to transport the storage shelf to the inventory restocking station at the retail facility; wherein the display shelf receives the inventory item at the inventory restocking station; after the inventory item is received by the display shelf at the inventory restocking station, the management module instructing the first mobile drive unit to transport the display shelf to a designated location within the retail facility. detecting, by the management module, that a display shelf at the retail facility is low on an inventory item and needs to be replenished with an inventory item, wherein the management module determines that an amount of inventory items in a display shelf has fallen below a predetermined threshold; determining, by the management module, that the inventory item is stored in a storage shelf at the retail facility; instructing, by the management module, the first mobile drive unit to transport the display shelf to the inventory restocking station at the retail facility; instructing, by the management module, the second mobile drive unit to transport the storage shelf to the inventory restocking station at the retail facility; wherein the display shelf receives the inventory item at the inventory restocking station; after the inventory item is received by the display shelf at the inventory restocking station, the management module instructing the first mobile drive unit to transport the display shelf to a designated location within the retail facility.