Many people coming to Zotero already have extensive collections stored in other reference management software. The following information describes how to make the move from EndNote to Zotero, but the same basic steps apply to many other reference management systems. For other programs, the BibTeX or RIS formats generally produce good results.
Zotero can't directly import “.enl” EndNote libraries, so the first step is exporting your library from EndNote. The best export format for this is XML.
It may be necessary, with older EndNote libraries, to convert figures to attachments before you export to a RIS file. This is done by going to the References menu > Figure and selecting “Convert Figures to File Attachments…”
If you are not importing into an empty library, we highly recommend making a backup of you Zotero data directory. This can avoid frustration if you do not like the way your library has transferred. In that event, simply restore your library from the backup.
You should also temporarily disable automatic sync in Zotero's Sync preferences. After you have imported your library and checked to be sure you are satisfied with the imported data, you can re-enable automatic sync.
In Zotero, click “Import…” in the “File” menu. A dialog box will appear asking you to select the file to import. Navigate to the location where you exported your EndNote library (if you followed the above instructions, this should be My Documents\endnote.Data) and select the XML file. Click Open.
The EndNote library will be imported into a separate collection. You may remove the collection (right-click → Delete Collection…) without deleting the imported references (they will remain in the root of your library).
Note, if Zotero encounters any fields in the Endnote XML data that it does not support (e.g., custom fields, author address, author affiliation), it will add these data to a note attached to the imported item. These notes will be tagged with “_EndnoteXML import”. If the import adds many of these notes, Zotero's performance can be negatively impacted. You should review each of these notes to determine if the data need to be retained (you can also move these data to the Zotero “Extra” field). Any unnecessary notes can be deleted. Additionally, you should check these notes to determine if any data could be migrated to proper Zotero fields (this is particularly important if you were using Endnote fields in non-standard ways).
You can quickly display all of the notes generated during import by clicking on the “_EndnoteXML import” tag in the tag selector in the lower-left corner of the Zotero window. You can quickly delete all of these notes by selecting the tag in the tag selector, clicking in the items list and typing Cmd+A (Mac) or Ctrl+A (Windows/Linux) to select all matching items, and then right-clicking on a selected item and choosing “Delete Selected Items from Library…”.
If you have any issues related to importing and exporting references, feel free to ask for help on the Zotero forums.
Instead of Endnote XML, it is also possible to export items from Endnote using RIS. The only benefit of RIS over XML is that the Endnote database ID can be retained for each item. If this is required, then, in Zotero, open the Advanced pane of Zotero preferences and click the “Config Editor” button on the “General” tab. Search for “RIS.import.keepID” and double-click to set it to true. If you want data for unknown fields to be retained in notes (as described above), also search for “RIS.import.ignoreUnknown” and set this option to true.
In Endnote, export your library as above, setting “Save as type:” to “Text file (.txt)”. Set “Output style:” to “RefMan (RIS)”. Navigate to your Endnote data folder (as described above), save the export file, then import into Zotero as described above.
With this setup, RIS will retain Endnote database IDs, but any italics, bold, or other formatting set in fields will be lost. XML should always be used unless Endnote database IDs are needed for a specific reason.