Thank you for looking at this humdingaling. The difference would be that the dates, wouldn't just be within a specified range, they would need to be compared to all the other dates in the column to see if any of the dates are within a range of any of the other dates. In effect it would be a moving goal post where it's comparing all dates against any other date to see if they are within a range of eachother. I can post a sample sheet if that would be helpful.