Thank you so much for your reply. It sounds like I should be able to add a new customer to my data source and create a new mail merge output document. That's promising. It sounds like I made a mistake somehow in adding the new customer data to the data source then. I did not apply a named range, and I tried putting the new data in a few different places (as the last row and as a new row in the middle of the data source) but that didn't seem to work. Any troubleshooting suggestions?