You want to use the CommonPath method of this RelativePath class. Once you have the common path, just strip it out of the path you want to display.
Namespace IO.Path Public NotInheritable Class RelativePath Private Declare Function PathRelativePathTo Lib "shlwapi" Alias "PathRelativePathToA" ( _ ByVal pszPath As String, _ ByVal pszFrom As String, _ ByVal dwAttrFrom As Integer, _ ByVal pszTo As String, _ ByVal dwAttrTo As Integer) As Integer Private Declare Function PathCanonicalize Lib "shlwapi" Alias "PathCanonicalizeA" ( _ ByVal pszBuf As String, _ ByVal pszPath As String) As Integer Private Const FILE_ATTRIBUTE_DIRECTORY As Short = &H10S Private Const MAX_PATH As Short = 260 Private _path As String Private _isDirectory As Boolean#Region " Constructors " Public Sub New() End Sub Public Sub New(ByVal path As String) _path = path End Sub Public Sub New(ByVal path As String, ByVal isDirectory As Boolean) _path = path _isDirectory = isDirectory End Sub#End Region Private Shared Function StripNulls(ByVal value As String) As String StripNulls = value If (InStr(value, vbNullChar) > 0) Then StripNulls = Left(value, InStr(value, vbNullChar) - 1) End If End Function Private Shared Function TrimCurrentDirectory(ByVal path As String) As String TrimCurrentDirectory = path If Len(path) >= 2 And Left(path, 2) = ".\" Then TrimCurrentDirectory = Mid(path, 3) End If End Function'''<summary>''' 3. conforming to general principles: conforming to accepted principles or standard practice'''</summary> Public Shared Function Canonicalize(ByVal path As String) As String Dim sPath As String sPath = New String(Chr(0), MAX_PATH) If PathCanonicalize(sPath, path) = 0 Then Canonicalize = vbNullString Else Canonicalize = StripNulls(sPath) End If End Function'''<summary>''' Returns the most common path between two paths.'''</summary>'''<remarks>'''<para>returns the path that is common between two paths</para>'''<para>c:\FolderA\FolderB\FolderC</para>''' c:\FolderA\FolderD\FolderE\File.Ext'''''' results in:''' c:\FolderA\'''</remarks> Public Shared Function CommonPath(ByVal path1 As String, ByVal path2 As String) As String'returns the path that is common between two paths'' c:\FolderA\FolderB\FolderC' c:\FolderA\FolderD\FolderE\File.Ext'' results in:' c:\FolderA\ Dim sResult As String = String.Empty Dim iPos1, iPos2 As Integer path1 = Canonicalize(path1) path2 = Canonicalize(path2) Do If Left(path1, iPos1) = Left(path2, iPos2) Then sResult = Left(path1, iPos1) End If iPos1 = InStr(iPos1 + 1, path1, "\") iPos2 = InStr(iPos2 + 1, path1, "\") Loop While Left(path1, iPos1) = Left(path2, iPos2) Return sResult End Function Public Function CommonPath(ByVal path As String) As String Return CommonPath(_path, path) End Function Public Shared Function RelativePathTo(ByVal source As String, ByVal isSourceDirectory As Boolean, ByVal target As String, ByVal isTargetDirectory As Boolean) As String'DEVLIB' 05/23/05 1:47PM - Fixed call to PathRelativePathTo, iTargetAttribute is now passed to dwAttrTo instead of IsTargetDirectory.' For Visual Basic 6.0, the fix does not change testing results,' because when the Boolean IsTargetDirectory is converted to the Long dwAttrTo it happens to contain FILE_ATTRIBUTE_DIRECTORY,' Dim sRelativePath As String Dim iSourceAttribute, iTargetAttribute As Integer sRelativePath = New String(Chr(0), MAX_PATH) source = Canonicalize(source) target = Canonicalize(target) If isSourceDirectory Then iSourceAttribute = FILE_ATTRIBUTE_DIRECTORY End If If isTargetDirectory Then iTargetAttribute = FILE_ATTRIBUTE_DIRECTORY End If If PathRelativePathTo(sRelativePath, source, iSourceAttribute, target, iTargetAttribute) = 0 Then RelativePathTo = vbNullString Else RelativePathTo = TrimCurrentDirectory(StripNulls(sRelativePath)) End If End Function Public Function RelativePath(ByVal target As String) As String Return RelativePathTo(_path, _isDirectory, target, False) End Function End ClassEnd Namespace