This question applies to multiple sheets in a workbook: I have a daily total for the whole year(across two sheets). To keep things simple, I'll reduce it for this thread. Sheet 1 and Sheet 2 have January, 1st in cell A1 and January 2nd in A2 of both sheets. I would like, if possible to set it up so data cannot be entered for January 2nd until data has been entered for January 1st across BOTH sheets. Subsequently, January 3rd (A3) [of any sheet] will not allow data until previous dates' data are entered. . It would apply for all dates for the whole year. Is that possible, or am I being too ambitious? Thanks in advance; let me know if I need to elucidate anything and/or submit anything else! ANY help will suffice. This forum has been a tremendous help! :D