In Office 2007, look under the 'Data' tab up in the ribbon. With the cell you
want to use for the drop-down menu selected, hit "Data Validation". Here you
can set the values users are allowed to enter into the cell - the drop-down
menus are under the option "Allow:List" in the validation categories. The
data for the list should be in the form of a range - either in the format
=$A$2:$A$20 which contain your different options, or in a named range with
the same options. Hope that helps.

"How do add Drop down list" wrote:

How do I add drop down list in my excel spreadsheet so that it would look
like a database where in I can choose options in a single cell.