Abstract: A bag holder device facilitates the reuse of bags such as plastic grocery bags as waste collection bags. The device has a body formed with slots from which the bag can be suspended by means of its handles. An expander element is pivotally connected to the body and is movable between a storage state in which it is folded against the body and a usable state in which it engages the interior of the bag to retain the mouth of the bag open for receiving waste. The device may be removably or non-removably attachable to a support surface or may be free-standing. It is conveniently formed from a washable, lightweight material.