With a bit of Excel VBA programming, you can change an Excel data validation drop down list, so it allows multiple selections. There is a sample file and instructions, in a blog post that I wrote a couple of years ago – Select Multiple Items from Excel Data Validation List.
There is a video in that post, that shows how the multiple selection options work, and a peek at the code that makes the multiple selections possible.
Setting up the Workbook
Even though the post is a couple of years old, it still gets comments and questions. This week, Rick asked for details on setting up a new workbook, and copying the sample code into the new file.
To help, I've recorded another video, showing the setup steps.
More Articles on Select Multiple Items
[Update]: Since posting this article on selecting multiple items from an Excel drop down list, I've added more articles on the same topic. Please read these updates, for more details on working with the VBA code:
Download the Sample Data Validation File
To experiment with this technique, you can download the zipped sample file from the Contextures website, on the Excel Data Validation - Select Multiple Items page.