Various embodiments of a system and method for an order handling data model with item-level granularity are described. Embodiments may include an order handling system configured to, for a given purchase order received from an ordering entity, generate within a data store a purchase order data object, item data objects for items of the purchase order, and message data objects for messages associated with item data objects. In various embodiments, the order handling system may also generate in the data store mapping information for mapping each of the different data objects for a given purchase order together. The order handling system may also provide to the ordering entity a notification for a particular item. The notification may be based on information accessed from the item data object corresponding to the particular item or information accessed from other data objects associated with that item data object according to the mapping information.