this.gridDataBoundGrid1.AllowResizeToFit = false;If you are trying to do this from RowExpanded, move your calls to this.gridDataBoundGrid1.Model.ColWidths under the grid.EndUpdate calls. This has to be done while the painting is not locked. A couple of other comments. Index 0 is the row header column, index 1 is the expand column, so your first column from your datasource is index 2 (and it shares a covered range with the expand column at index 1). So you need to take this into account as you set the widths. The second comment is that there is a single set of colwidths for the grid, and they apply to all levels.