Abstract: A toolbox fabricated from semi-rigid polymeric material includes a base portion that is strapable to the uppermost step of a folding step ladder, a storage portion unitary with the base portion, and a hinged cover portion which is sized to reversably cover the storage portion. The base portion includes multiple slot-like apertures, through which flexible straps may be inserted. When the toolbox has been mounted on the top step of a step ladder, the straps may be used to secure the toolbox to the step by securing the ends of each strap beneath the step. Though many types of strap fasteners are known in the art, hook and look fasteners are considered to be the most economical means of securing the strap ends. The storage portion of the tool box includes multiple bin-type storage compartments which are intended to store tools, supplies, small equipment and parts for tasks which are typically performed while standing on a ladder.