Off the top of my head, in your beforeupdate event, can you check the OldValue property? If it is Null, then the user is entering data for the first time and everything is OK, but if the OldValue is not Null then undo.<br><br>Here is the code to put in the BeforeUpdate event <br><br> If Not (IsNull(Me!YourControlName.OldValue)) Then<br> <br> MsgBox "You cannot change a value once it has been entered!"<br> Cancel = True<br> Me!YourControlName.Undo<br> End If<br><br>Hope that helps. <p>Kathryn<br><a href=mailto: > </a><br><a href= > </a><br>