procedure TForm1.FormCreate(Sender: TObject); 
begin 
  MonthCalendar1.Multiselect := true; 
end; 
 
procedure TForm1.MonthCalendar1Click(Sender: TObject); 
var 
  x: integer; 
begin 
  Listbox1.items.clear; 
  with TMonthCalendar(Sender) do 
    for x := trunc(Date) to trunc(EndDate) do 
      Listbox1.items.add(datetostr(x)); 
end; 
 
procedure TForm1.FormShow(Sender: TObject); 
begin 
  MonthCalendar1Click(Sender); 
end;