For a multiple-selection list_box, this property returns a collection containing all items that are selected in the list_box. For a single-selection list_box, this property returns a collection containing a single element containing the only selected item in the list_box. For more information about how to manipulate the items of the collection, see list_box::selected_object_collection.
The list_box class provides a number of ways to reference selected items. Instead of using the selected_items property to obtain the currently selected item in a single-selection list_box, you can use the selected_item property. If you want to obtain the index position of an item that is currently selected in the list_box, instead of the item itself, use the selected_index property. In addition, you can use the selected_indices property if you want to obtain the index positions of all selected items in a multiple-selection list_box.