This should do it.
VB Code:
  1. Option Explicit
  2.  
  3. Private Sub Form_Load()
  4.   Dim x As Integer
  5.   For x = 0 To list1.ListCount - 1
  6.     If list1.List(x) = LCase(list1.List(x)) Then
  7.       list2.AddItem list1.List(x) ' all lowercase
  8.     Else
  9.       list3.AddItem list1.List(x) ' mixes case
  10.     End If
  11.   Next x
  12. End Sub