diff --git a/Common.Wpf.csproj b/Common.Wpf.csproj
index 09abecf..c71e7af 100644
--- a/Common.Wpf.csproj
+++ b/Common.Wpf.csproj
@@ -154,7 +154,7 @@
   </ItemGroup>
   <ItemGroup>
     <Compile Include="CheckedListItem.cs" />
-    <Compile Include="EnumToResourceConverter.cs" />
+    <Compile Include="Resource\EnumToResourceConverter.cs" />
     <Compile Include="ExtendedListBoxControl\ExtendedListBox.cs" />
     <Compile Include="ExtendedListBoxControl\ExtendedListBoxItem.cs" />
     <Compile Include="Extensions\ApplicationExtensions.cs" />
@@ -181,7 +181,7 @@
     <Compile Include="HtmlLabelControl\TextFragmentStyle.cs" />
     <Compile Include="HtmlLabelControl\TextParser.cs" />
     <AppDesigner Include="Properties\" />
-    <Compile Include="RepositionPopupBehavior.cs" />
+    <Compile Include="Validation\RepositionPopupBehavior.cs" />
     <Compile Include="TextListControl\TextList.xaml.cs">
       <DependentUpon>TextList.xaml</DependentUpon>
     </Compile>
@@ -190,6 +190,7 @@
       <DependentUpon>ImageButton.xaml</DependentUpon>
     </Compile>
     <Compile Include="Toolbar\SplitButton\SplitButton.cs" />
+    <Compile Include="Validation\ValidationModelBase.cs" />
     <Compile Include="Windows\ControlBox.cs" />
     <Compile Include="Windows\SnappingWindow.cs" />
     <Compile Include="Windows\WindowInformation.cs" />
@@ -221,7 +222,7 @@
       <Generator>MSBuild:Compile</Generator>
       <SubType>Designer</SubType>
     </Page>
-    <Page Include="ValidationResources.xaml">
+    <Page Include="Validation\ValidationResources.xaml">
       <SubType>Designer</SubType>
       <Generator>MSBuild:Compile</Generator>
     </Page>
diff --git a/Extensions/WindowExtensions.cs b/Extensions/WindowExtensions.cs
index 5c5a517..206be9b 100644
--- a/Extensions/WindowExtensions.cs
+++ b/Extensions/WindowExtensions.cs
@@ -102,7 +102,7 @@ namespace Common.Wpf.Extensions
         public static void ClearAllValidationErrors(this DependencyObject window, IEnumerable<BindingExpressionInfo> bindingExpressions)
         {
             foreach (var expression in bindingExpressions)
-                Validation.ClearInvalid(expression.BindingExpression);
+                System.Windows.Controls.Validation.ClearInvalid(expression.BindingExpression);
         }
 
         public static bool Validate(this Window window)
diff --git a/EnumToResourceConverter.cs b/Resource/EnumToResourceConverter.cs
similarity index 96%
rename from EnumToResourceConverter.cs
rename to Resource/EnumToResourceConverter.cs
index 3104fd3..1112791 100644
--- a/EnumToResourceConverter.cs
+++ b/Resource/EnumToResourceConverter.cs
@@ -3,7 +3,7 @@ using System.Globalization;
 using System.Resources;
 using System.Windows.Data;
 
-namespace Common.Wpf
+namespace Common.Wpf.Resource
 {
     public class EnumToResourceConverter : IValueConverter
     {
diff --git a/RepositionPopupBehavior.cs b/Validation/RepositionPopupBehavior.cs
similarity index 99%
rename from RepositionPopupBehavior.cs
rename to Validation/RepositionPopupBehavior.cs
index bf6352c..8b0a906 100644
--- a/RepositionPopupBehavior.cs
+++ b/Validation/RepositionPopupBehavior.cs
@@ -3,7 +3,7 @@ using System.Windows;
 using System.Windows.Controls.Primitives;
 using System.Windows.Interactivity;
 
-namespace Common.Wpf
+namespace Common.Wpf.Validation
 {
     /// <summary>
     /// Defines the reposition behavior of a <see cref="Popup"/> control when the window to which it is attached is moved or resized.
diff --git a/Validation/ValidationModelBase.cs b/Validation/ValidationModelBase.cs
new file mode 100644
index 0000000..56e58e3
--- /dev/null
+++ b/Validation/ValidationModelBase.cs
@@ -0,0 +1,86 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Runtime.CompilerServices;
+
+namespace Common.Wpf.Validation
+{
+    public class ValidationModelBase : INotifyPropertyChanged, INotifyDataErrorInfo
+    {
+        #region Property changed
+        public event PropertyChangedEventHandler PropertyChanged = delegate { };
+
+        protected void NotifyPropertyChanged(string propertyName)
+        {
+            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
+        }
+        #endregion
+
+        #region Notify data error
+        private readonly Dictionary<string, List<string>> _errors = new Dictionary<string, List<string>>();
+        public event EventHandler<DataErrorsChangedEventArgs> ErrorsChanged = delegate { };
+
+        // get errors by property
+        public IEnumerable GetErrors(string propertyName)
+        {
+            if (_errors.ContainsKey(propertyName))
+                return _errors[propertyName];
+            return null;
+        }
+
+        // has errors
+        public bool HasErrors
+        {
+            get { return (_errors.Count > 0); }
+        }
+
+        // object is valid
+        public bool IsValid
+        {
+            get { return !HasErrors; }
+
+        }
+
+        public void AddError(string error, [CallerMemberName] string propertyName = null)
+        {
+            if (propertyName == null)
+                return;
+
+            // Add error to list
+            _errors[propertyName] = new List<string> { error };
+            NotifyErrorsChanged(propertyName);
+        }
+
+        public void RemoveError([CallerMemberName] string propertyName = null)
+        {
+            if (propertyName == null)
+                return;
+
+            // remove error
+            if (_errors.ContainsKey(propertyName))
+                _errors.Remove(propertyName);
+
+            NotifyErrorsChanged(propertyName);
+        }
+
+        private void NotifyErrorsChanged(string propertyName)
+        {
+            ErrorsChanged(this, new DataErrorsChangedEventArgs(propertyName));
+        }
+
+        #endregion
+
+        protected void SetProperty<T>(ref T propertyValue, T newValue, [CallerMemberName] string propertyName = null)
+        {
+            if (Equals(propertyValue, newValue))
+                return;
+
+            propertyValue = newValue;
+            NotifyPropertyChanged(propertyName);
+            NotifyErrorsChanged(propertyName);
+        }
+
+
+    }
+}
diff --git a/ValidationResources.xaml b/Validation/ValidationResources.xaml
similarity index 96%
rename from ValidationResources.xaml
rename to Validation/ValidationResources.xaml
index ea689c7..77d3870 100644
--- a/ValidationResources.xaml
+++ b/Validation/ValidationResources.xaml
@@ -1,7 +1,7 @@
 <ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                     xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
-                    xmlns:wpf="clr-namespace:Common.Wpf">
+                    xmlns:validation="clr-namespace:Common.Wpf.Validation">
     <ControlTemplate x:Key="ValidationTemplate">
         <StackPanel Orientation="Horizontal">
             <!-- Defines TextBox outline border and the ToolTipCorner -->
@@ -39,7 +39,7 @@
                    PlacementRectangle="10,-1,0,0">
                 <!-- Used to reposition Popup when dialog moves or resizes -->
                 <i:Interaction.Behaviors>
-                    <wpf:RepositionPopupBehavior />
+                    <validation:RepositionPopupBehavior />
                 </i:Interaction.Behaviors>
                 <Popup.Style>
                     <Style TargetType="{x:Type Popup}">