Maybe you can pick up something from Debra Dalgleish's sample workbook:
http://www.contextures.com/excelfiles.html#DataVal

Look for:
Select Multiple Items from Dropdown List-- Select multiple items from a
dropdown list; an event macro stores selections in adjacent cell, or in same
cell. DataValMultiSelect.xls 39kb

microchick wrote:

I am trying to set up dropdown lists in MS Excel using the data validation
function. Is there a way that I can set up the list so that the user is able
to chose more than 1 choice from my list? You see this on websites often.

--

Dave Peterson