That worked! Thanks Darrell. I am little surprised though with the name of the property. It's sometimes hard to figure out the functionality based on the name. Thanks anyway!

I made a mistake, 

FirstSortDirection changes what direction the grid / column will sort the first time you click on an unsorted column.

If you want to sort a column set the IsSorted property on the column.

      <ig:XamGrid x:Name="tree" AutoGenerateColumns="false">

            <ig:XamGrid.Columns>

                <ig:TextColumn Key="FName"   HeaderText="blah" IsSorted="Ascending"   ></ig:TextColumn>

                <ig:TextColumn Key="LName" ></ig:TextColumn>

            </ig:XamGrid.Columns>            

        </ig:XamGrid>

Thanks Darrell for the quick response. I am able to sort by a certain column by setting this property. But, it seems the grid is also getting sorted by another column that doesn't have this property. For example, i have two columns rank and source. I am setting the FirstSort property of rank to ascending. The results are displayed as multi sorted first by Rank and then by Source automatically. Should i set any other property of the grid to fix this? Many thanks!!