Probably going to need to see some more code Pete. The DataGridViewTextBoxColumn is sub-classed from DataGridViewColumn, so it should all be able to cast ok. I just think you're not going to be able to add columns from the designer, but in your own code.

~~Bonnie



>Hi Bonnie, sorry for the slow response - we have had serious snow here in the UK so my Web time has been seriously reduced - here is my class.
>
>

>public class MyDataGridViewTextBoxColumn:DataGridViewTextBoxColumn
>    {
>        public MyDataGridViewTextBoxColumn()
>        {
>        }
>    } 
>