>>e.Column.Header gives me "Invoice #", but if I then change the # to "Number" because that's what the client wants then my code breaks. I can't see anything in there that gives me "txtInv_Number"
>
>Don't know if you can get that. Bit ugly but could you depend on the binding? :

DataGridBoundColumn b = e.Column as DataGridBoundColumn;
>            var v = b.Binding as System.Windows.Data.Binding;
>            if (v.Path.Path == "crt_invfk")
>            {
>               //This is the column
>            }

thanks Viv, that works for me!