Thanks, ChevolDavis.

I don't want to be constrained by having to know the cell number. That
is, I want to leave freedom in the design to rearrange the columns of
the datagrid, without having to change the code.

I am having some success with the code below, making use of the
boundField property of the DataGridColumnCollection and a hash table to
act as an index. If anyone has further suggestions I would still like
to hear them!

Jacque

public void OnDataBindValuesCheck (object sender, DataGridItemEventArgs
e)
{
   TableCell objectCell = new TableCell();
 int cell_index;

// Cast the sender as a DataGrid object.
 DataGrid replicadgBedSize = new DataGrid();
 replicadgBedSize = ((DataGrid)sender);
// Not quite sure why, but an ArrayList is
// needed to create the DataGridColumnCollection.
 ArrayList alC = new ArrayList();
// Get the DataGridcolumnCollection
// object from the sender DataGrid
 DataGridColumnCollection dgcc = new
DataGridColumnCollection(((DataGrid)sender), alC);
 dgcc = replicadgBedSize.Columns;
// Create a hash table to use as an index to the columns
 Hashtable cell_datafield = new Hashtable();
 int count = 0;
 foreach (BoundColumn c in dgcc)
 {
   cell_datafield[c.DataField.ToString()] = count;
   count++;
 }

// Now the hashtable can be
// used to look up the column
// name and return it's location
// in the data grid
 if (/*data in a particular column "ColumnName" meets a condition*/)
 {
   cell_index = Convert.ToInt32(cell_datafield["ColumnName"]);
   objectCell = e.Item.Cells[cell_index];
   objectCell.BackColor = System.Drawing.Color.Red;
 }
}