Before trying any of the instructions below you must make sure your version of Word is updated to at least 12.1.0, but 12.2.0 is recommended.
To check which version of Word you have, click the 'Word' titlebar menu > 'About Word'. See what it says next to 'Version'.

To update Word you can click 'Help' > 'Check for Updates' or use your web browser to navigate to http://www.microsoft.com/mac/downloads.mspx

If this does not resolve your problem, please perform the following:

1. Run the EndNote customiser. In EndNote X2 or X3 navigate to
'EndNote X2/X3' titlebar menu > Customizer > tick 'Cite While you Write' and press 'Next'.

N.B. If you've installed Word 2008 to anywhere other than the default place in the Applications folder, you'll need to tell EndNote where you've installed it. If you installed Word to the default place or if you're unsure, just press 'Next'.

If this fails, you need to manually install the cite While You Write tools. Close Word and EndNote, then:

1. Navigate to Applications:EndNote X2/X3:Cite While You Write

2. Find the file EndNote CWYW Word 2008.bundle and copy it

3. Navigate to Applications:Microsoft Office 2008:Office:Startup:Word and paste the bundle file into this location.

N.B. In non-English versions of Word, the folder named Startup may be called Start or be in the localised language of Word.

4. Start Word, go to 'Word' > 'Preferences' and click on 'File Locations'

5. If the Startup folder is not set, highlight 'Startup' and click on 'Modify'.

6. Select the folder Applications:Microsoft Office 2008:Office:Startup:Word and click 'Choose'.

7. Click OK and close Word.

8. Start EndNote, open a library, then start Word.