Hey thanks for your response

Yes that's what i thought but i can't work out how to do it, which is really bizarre when you consider how much conditional formatting I've already used.

Basically I have tabs marked Jan - Dec and on each tab there are columns for each date in that month. This workbook is being distributed to different departments and some of them need Sundays blacked out and some don't, but I'd like them to be able to do it themselves from the welcome worksheet with the use of a "button", but I just can't work out how to do it.

Thanks
Denise