An index tab adapter, suitable for retrofitting an existing file folder for use with a particular index tab style. The adapter has adhesive portions, located on either side of a non-adhesive portion. The non-adhesive portion is slotted and is spaced apart from the file folder. The slots are shaped to engage a particular style of index tab, so that when a given index tab is inserted into the slots in the adapter, the given index tab becomes attached to the file folder, and the file folder may be identified by the given index tab as if it were originally configured to accept the style of the given index tab. Put another way, an index tab removably engages slots in the adapter, rather than slots in the file folder itself.