No Duplicates on Data Entry in Access

In Microsoft Access, I have one table and am entering new records. As I enter new records, I would like to set up some type of syntax or validation rule where if an address is entered it is not a duplicate of another record. For example, if 1500 Snowcreek Rd, Waterbury, TX 88888 is in another record and I try to enter that same address in a new record it will bring up a message telling me that address is already entered.