Thanks for your respons Karl. Let me know if I'm reading this right. From your example above, does:
1. Name = the name of the field listing the names.
2. Other Table = Subsitute the name of the other table in place of this.
3. Phone number = Subsitute the name of the phone number field.
I typed this in and keep getting a Runtime error '620506' - Data type mismatch in criteria expression.
Me!FirstName = DLookup("FirstName", "tblSecondary", "[AccountNumber] = """ & Me![AccountNumber] & """")
Instead of a phone number I'm using a account number to updated a field called FirstName, LastName, etc. All the data is in a table called tblSecondary. What am I doing wrong???