1. Go to Analysis > Information Library.  Click Add an ad-hoc query.  Select the source view of Constituents and click Ok.
  2. On the left, click on the plus sign next to Registrant, then click on Event.  
  3. In the middle, click on Event Record and move this to Include Records Where.  Set the criteria equal to the event.
  4. On the left, click on the plus sign next to Invitee, then click on Event.  
  5. In the middle, click on Event Record and move this to Include Records Where.  Set the criteria equal to the event.
  6. In the Include Records Where section, click on the first line of criteria (Registrant\event\event record is equal to X) and click on the Add left parentheses button.
  7. Then, click on the second line of criteria (Invitee\Event\Event Record is equal to X) and click the OR button, then the Add right parentheses button.
  8. Move anything you want to see to Results Fields to Display.
  9. Go to the Set Save options tab, name and save the query.