When I needed to something like that, I found my answer on this web site.

http://www.contextures.com/excelfiles.html#DataVal


"Shawna" wrote:

I have 6 categories with 5-8 subcategories for each. My worksheet is a
document log. On my worksheet I have a column for Categories and a column for
Sub-Categories. I want a drop down box under categories that only returns the
available categories. And when I choose that category I was a drop down box
under Sub Category to ONLY return the subcategories lists under the category
in the cell before.
Categories & Sub Categories:
Est. Budget-EWD's Contractual
Estimate Contractual
Budger/SUV Change Orders
Billings & EWD Backups Budget Revisions
EWD Estimates Cost Reports
Cost Projections PSR's / PCS
Anticipated Change Orders & ROM Misc

Top row is the category. Worksheet:
Drawer Number Box Number Category Sub Category

Is this possible?