<StackPanel Grid.IsSharedSizeScope="True">
  <!-- Header -->
  <Grid>
    <Grid.ColumnDefinitions>
      <ColumnDefinition Width="Auto" SharedSizeGroup="Column1" />
      <ColumnDefinition Width="Auto" SharedSizeGroup="Column2" />
    </Grid.ColumnDefinitions>
    <TextBlock Grid.Column="0" Text="Column Header 1" />
    <TextBlock Grid.Column="1" Text="Column Header 2" />
  </Grid>
  <!-- Items -->
  <ItemsControl ItemsSource="{Binding Path=Values, Mode=OneWay}">
    <ItemsControl.ItemTemplate>
      <DataTemplate>
        <Grid>
          <Grid.ColumnDefinitions>
            <ColumnDefinition Width="Auto" SharedSizeGroup="Column1" />
            <ColumnDefinition Width="Auto" SharedSizeGroup="Column2" />
          </Grid.ColumnDefinitions>
          <TextBlock Grid.Column="0" Text="{Binding ColumnProperty1}" />
          <TextBlock Grid.Column="1" Text="{Binding ColumnProperty2}" />
        </Grid>
      </DataTemplate>
    </ItemsControl.ItemTemplate>
  </ItemsControl>
</StackPanel>