For CheckedListBoxes, multi-selection is not supported. You can set selection to be able to select one item or no items.
[Visual Basic] Overridable Public Property SelectionMode As SelectionMode [C#] public SelectionMode SelectionMode {override get; override set;} [C++] public: __property virtual SelectionMode get_SelectionMode(); public: __property virtual void set_SelectionMode(SelectionMode); [JScript] public function get SelectionMode() : SelectionMode; public function set SelectionMode(SelectionMode);
CheckedListBox Class | CheckedListBox Members | System.WinForms Namespace