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.
How to Import From EndNote
In EndNote, select “Output Styles” from the Edit menu. From the list of output styles select RefMan (RIS). (If you do not see RIS as an option, you’ll need to download the style from the EndNote site.) It could also be that the style is not enabled. You may have to go open the Output Styles Manager from the Edit menu, enable RIS, then close the manager before it’s an option.) Once RefMan (RIS) is set as the format, select “Export” from the File menu. In the Export window that pops up, choose “Text Only”, select the RIS output style immediately below “Text Only” in the dialog, and hit “Save.” After exporting from EndNote, click on the gear icon () above the left column in your Zotero pane and select Import from the pull-down menu. In the filesystem window that pops up, locate the RIS file you exported from EndNote and select “Open.” Your references should be imported into Zotero.
If you have any issues related to importing and exporting references, try searching the forums. You may well find quick tips to help you solve your problem. If your search doesn’t turn up the answer you were looking for, post your question to the forums. This is the quickest way to get information from the Zotero team.