<Grid xmlns:xcdg="http://schemas.xceed.com/wpf/xaml/datagrid"
     xmlns:local="clr-namespace:Xceed.Wpf.Documentation">
  <Grid.Resources>
     <xcdg:DataGridCollectionViewSource x:Key="cvs_composers"
                                        Source="{Binding Source={x:Static Application.Current},
                                                         Path=Composers}"/>
  </Grid.Resources>
 
  <xcdg:DataGridControl ItemsSource="{Binding Source={StaticResource cvs_composers}}"
                        UpdateSourceTrigger="RowEndingEdit">
     <xcdg:DataGridControl.Columns> 
       <xcdg:Column FieldName="BirthYear">
          <xcdg:Column.DisplayMemberBindingInfo>
             <xcdg:DataGridBindingInfo Path="BirthYear">
                <xcdg:DataGridBindingInfo.ValidationRules>
                   <local:YearValidationRule />
                </xcdg:DataGridBindingInfo.ValidationRules>
             </xcdg:DataGridBindingInfo>
          </xcdg:Column.DisplayMemberBindingInfo>
       </xcdg:Column>

       <xcdg:Column FieldName="DeathYear">
          <xcdg:Column.DisplayMemberBindingInfo>
             <xcdg:DataGridBindingInfo Path="DeathYear">
                <xcdg:DataGridBindingInfo.ValidationRules>
                   <local:YearValidationRule />
                </xcdg:DataGridBindingInfo.ValidationRules>
             </xcdg:DataGridBindingInfo>
          </xcdg:Column.DisplayMemberBindingInfo>
       </xcdg:Column>     
    </xcdg:DataGridControl.Columns>
  </xcdg:DataGridControl>
</Grid>

VB.NET

Imports System
Imports System.Windows.Controls
Imports System.Globalization

Namespace Xceed.Wpf.Documentation
  Public Class YearValidationRule
               Inherits ValidationRule

    Public Overrides Function Validate( ByVal value As Object, _
                                        ByVal cultureInfo As CultureInfo ) As ValidationResult
      Dim year As Integer = CInt( value )

      If year > DateTime.Now.Year Then
        Return New ValidationResult( False, "Chosen year cannot be greater than this year." )
      End If
      Return ValidationResult.ValidResult
    End Function
  End Class
End Namespace

C#

using System;
using System.Windows.Controls;
using System.Globalization;

namespace Xceed.Wpf.Documentation
{
 public class YearValidationRule : ValidationRule
 {
   public override ValidationResult Validate( object value, CultureInfo cultureInfo )
   {
     int year = ( int )value;

     if( year > DateTime.Now.Year )
       return new ValidationResult( false, "Chosen year cannot be greater than this year." );

     return ValidationResult.ValidResult;
   }
 }
}