I have a list of holidays for a given year (E10-E16). I also have a table which represents the sequential weeks of the year; Weeks 1-52 (B2-M3 is a portion of this table). This table has a column for each week of the year. The first two rows of the table contain the date of the Monday and the Friday in that week e.g. 1/2/2017 and 1/6/2017 respectively for the 1st week of 2017. What I want to achieve is.... for each week, given the "start" and "end" dates for that week, look through the list of holidays and see if any holiday falls between the "start" and "end" dates for that week. If so, I want to know the INDEX of the date within the list of holidays that falls between those two dates. In the example below, I would have a formula in cells B4-M4 that would use this data to indicate whether or not a holiday falls within each week. e.g. D4 and K4 indicate holidays. Thanks in advance for your help!