One way to do it would be to use sumproduct
=sumproduct(--(A1:A100<=datevalue(D1)),--(B1:B100=Datevalue(D1)),C1:C100)

"Corissa" wrote:

I have the following data:
Col A = Start Date
Col B = End Date
Col C = Week Number

Is there a way to do a lookup function to display the Week Number if a user
enters a date that is between Col A and Col B?